iOS (iPhone, iPad) Tutorial

iOS is a mobile operating system developed and distributed by Apple Inc. Originally released in 2007 for the iPhone, iPod Touch, and Apple TV. iOS is derived from OS X, with which it shares the Darwin foundation. iOS is Apple's mobile version of the OS X operating system used on Apple computers.

iOS - Getting Started

General Overview

iOS which was previously called iPhone OS is a mobile operating system developed by Apple Inc. Its first release was in 2007 which included iPhone and iPod Touch. iPad (1st Generation) was released in the April 2010 and in iPad mini was released in November 2012

The iOS devices get evolved quite frequently and from the experience we find that at least one version of iPhone and iPad is launched every year. Now we have iphone5 launched which has its predecessors starting from iPhone, iPhone 3gs, iPhone 4, iPhone 4s. Similarly iPad has evolved from iPad (1st Generation) to iPad(4th Generation) and an additional iPad mini version.

The iOS SDK has evolved from 1.0 to 6.0. iOS 6.0, the latest SDK is the only officially supported version in Xcode 4.5 and higher. We have rich apple documentation and we can find which methods and libraries can be used based on our deployment target. In the current version of Xcode, we’ll be able to choose between deployment targets of iOS 4.3, 5.0 and 6.0..

The power of iOS can be felt with some of the following features provided part of the device.

Maps
Siri
Facebook and Twitter
Multi-Touch
Accelerometer
GPS
High end processor
Camera
Safari
Powerful APIs
Game center
In-App Purchase
Reminders
Wide Range of gestures

The number of users using iPhone/iPad has increased a great deal. This creates the opportunity for developers to make money by creating applications for iPhone and iPad the Apple's App Store.

For some one new to iOS, Apple has designed an application store where the user can buy apps developed for their iOS devices. A developer can create both free and paid apps to App Store. To develop applications and distribute to the store the developer will require to register with iOS developer program which cost $99 a year and a Mac with Mountain Lion or higher for its development with latest Xcode.

Registering as an Apple developer

An apple ID is most necessary if you are having any apple device and being a developer, you definitely need it. It's also free and hence no issues in having one. The benefits of having an apple account are as follows,

Access to development tools
Worldwide Developers Conference (WWDC) videos
Can join iOS developer program teams when invited

To register an apple account for you

1. Click the link (https://developer.apple.com/programs/register/) and select "Create Apple ID"

2. Provide the necessary information which is self explanatory as given in the page.

3. Verify your account with your email verification and account becomes active.

4. Now you will be able to download the developer tools like Xcode which is packaged with iOS simulator and iOS SDK, and other developer resources.

Apple iOS Developer Program

The first question that would arise to a new developer is why I should register for iOS developer program. The answer is quite simple; Apple always focuses on providing quality applications to its user. If there was no registration fee there could be a possibility of junk apps being uploaded and cause problem for app review team of Apple.

The benefits of joining iOS developer program are as follows,

Run the apps you develop on the real iOS device
Distribute the apps to app store
Get access to developer previews

The steps to join iOS developer program are as follows

1. To register click (https://developer.apple.com/programs/ios/)

2. Click enroll now in the page that is displayed

3. Then you can either sign in to your existing apple account (if you have one) or create a new Apple ID.

4. Then you have to select between Individual and Company accounts. Use company account if there will be more than one developer in your team. In individual account you can't add members.

5. Then after entering the personal information (for those who newly registers), you can purchase and activate the program by paying with the help of your credit card (Only accepted mode of payment).

6. Now you will get access to developer resources by selecting the member center option in the page.

7. Here you will be able to do the following,

Create provisioning profiles
Manage your team and devices
Managing application to app store through iTunes Connect
Get forum and technical support

iOS - Environment Setup

iOS - Xcode Installation

1. Download Xcode latest version from (https://developer.apple.com/downloads/)

2. Double click the Xcode dmg file.

3. You will find a device mounted and opened.

4. Here there will be two items in the window that's displayed namely Xcode application and the Application folder's shortcut.

5. Drag the Xcode to application and it will be copied to your applications.

6. Now Xcode will be available part of other applications from which you can select and run.

You also have another option of downloading Xcode from the Mac App store and then install following the step by step procedure given in the screen.

Interface Builder

Interface builder is the tool that enables easy creation of UI interface. You have a rich set of UI elements that is developed for use. You have just drag and drop into your UI view. We'll learn about adding UI elements, creating outlets and actions for the UI elements in the upcoming pages.

You have objects library in right bottom that consists the entire necessary UI element. The user interface is often referred as xibs which is their file extension. Each of the xibs is linked to a corresponding view controller.

iOS simulator

iOS simulator actually consists of two types of devices namely iPhone and iPad with its different versions. iPhone versions include iPhone (normal), iPhone Retina, iPhone 5 .iPad has iPad and iPad Retina. iPhone simulator is displayed below.

You can simulate location in iOS simulator for playing around with latitude and longitude effects of the app. You can also simulate memory warning and in-call status in the simulator. You can be able to use the simulator for most purposes. But you cannot test the device features like accelerometer. So you might always need an iOS device to test thoroughly on all aspect and scenarios of an application.

iOS - Objective C

Introduction

The language used in iOS development is objective C. It is an object oriented language and hence it would easy for those who have some background in object oriented language programming.

Interface and Implementation

In objective C the file where the declaration of class is done is called the interface file and the file where the class is defined is called the implementation file.

A simple interface file MyClass.h would look like the following.

@interace MyClass:NSObject{ 
// class variable declared here
}
// class properties declared here
// class methods and instance methods declared here
@end

The implementation file MyClass.m would be like follows

@implementation MyClass
// class methods defined here
@end

Object Creation

Object creation is done as follows

MyClass  *objectName = [[MyClass alloc]init] ;

Methods

Method is declared in objective C as follows

-(returnType)methodName:(typeName) variable1 :(typeName)variable2;

An example is shown below

-(void)calculateAreaForRectangleWithLength:(CGfloat)length 
andBreadth:(CGfloat)breadth;

You might be wondering what the andBreadth string for; actually its optional string which helps us read and understands the method easier especially at the time of calling. To call this method in the same class we use the following statement

[self calculateAreaForRectangleWithLength:30 andBreadth:20];

As said above the use of andBreadth helps us understand that breath is 20. Self is used to specify it's a class method.

Class method

Class methods can be accessed directly without creating objects for the class. They don't have any variables and objects associated with it. An example is shown below.

+(void)simpleClassMethod;

It can be accessed by using the class name (let's assume the class name as MyClass) as follows.

[MyClass simpleClassMethod];

Instance methods

Instance methods can be accessed only after creating an object for the class. Memory is allocated to the instance variables. An example instance method is shown below.

-(void)simpleInstanceMethod;

It can be accessed after creating an object for the class as follows

MyClass  *objectName = [[MyClass alloc]init] ;
[objectName simpleInstanceMethod];

Important data types in Objective C

S.N.	Data Type
1	NSString It is used for representing a string
2	CGfloat It is used for representing a floating point value (normal float is also allowed but it's better to use CGfloat)
3	NSInteger It is used for representing integer
4	BOOL used for representing Boolean(YES or NO are BOOL types allowed )

Printing logs

NSLog - used for printing a statement. It will be printed in device logs and debug console in release and debug modes respectively.

Eg: NSlog(@"");

Control Structures

Most of control structures are same as in C and C++ except for a few additions like for in statement.

Properties

For an external class to access class variables properties are used

Eg: @property(nonatomic , strong) NSString *myString;

Accessing Properties

You can use dot operator to access properties. To access the above property we will do the following.

self.myString = @"Test";

You can also use set method as follows.

[self setMyString:@"Test"];

Arrays

NSMutableArray and NSArray are the array classes used in objective C. As the name suggests the former is mutable and latter is immutable. An example is shown below.

NSMutableArray *aMutableArray = [[NSMutableArray alloc]init];
[anArray addObject:@"firstobject"];
NSArray *aImmutableArray = [[NSArray alloc]
initWithObjects:@"firstObject",nil];

Dictionary

NSMutableDictionary and NSDictionary is the dictionary classes used in objective C. As the name suggests the former is mutable and latter is immutable. An example is shown below.

NSMutableDictionary*aMutableDictionary = [[NSMutableArray alloc]init];
[aMutableDictionary setObject:@"firstobject" forKey:@"aKey"];
NSDictionary*aImmutableDictionary= [[NSDictionary alloc]initWithObjects:[NSArray arrayWithObjects:
@"firstObject",nil] forKeys:[ NSArray arrayWithObjects:@"aKey"]];

iOS - First iPhone Application

Creating our First App

Now we are just going to create a simple single view application (a blank app) that just runs on the iOS simulator.

The steps are as follows.

1. Open Xcode and select create a new Xcode project.

2. Then select single view application

3. Then enter product name i.e. the name of the application, organization name and then the company identifier

4. Ensure Use automatic reference counting is selected in order to automatically release the resources allocated once it goes out of scope. Click Next.

5. Select the directory for the project and select create.

6. You will see a screen as follows

In the screen above you will able to select the supported orientations, build and release settings. There is a field deployment target, the device version from which we want to support, lets select 4.3 which is the minimum deployment target allowed now. For now these are not required and let's focus on running the application.

7. Now select iPhone simulator in the drop down near Run button and select run.

8. That's it; you have successfully run your first application. You will get an output as follows

Now let's change the background color, just to have a start with interface builder. Select ViewController.xib. Select background option in the right side, change the color and run.

In the above project, by default the deployment target would have been set to iOS 6.0 and auto layout will be enabled. But to ensure our application to run on devices that run iOS 4.3 onwards, we have already modified the deployment target at the start of creation of this application but we didn't disable auto layout, to disable auto layout we need to deselect the auto layout checkbox in file inspector of each nib i.e the xib files. The various sections of Xcode project IDE are given in the following figure (Courtesy: Apple Xcode 4 User documentation).

File inspector is found in the inspector selector bar as shown above and auto layout can be unchecked there. Auto layout can be used when you want to target only iOS 6 devices. Also you'll be able to use many new features like passbook if you raise the deployment target to iOS 6. For now let's stick to iOS 4.3 as deployment target.

Digging deep into the code of the First iOS application

You will find 5 different files that would have been generated for your application. They are listed as follows.

AppDelegate.h
AppDelegate.m
ViewController.h
ViewController.m
ViewController.xib

We use these single line comments (//) to give simple code explanations and important items explained below the code.

AppDelegate.h

// Header File that provides all UI related items. 
#import <UIKit/UIKit.h> 
 // Forward declaration (Used when class will be defined /imported in future)
@class ViewController;  

 // Interface for Appdelegate
@interface AppDelegate : UIResponder <UIApplicationDelegate>
// Property window 
@property (strong, nonatomic) UIWindow *window; 
 // Property Viewcontroller
@property (strong, nonatomic) ViewController *viewController;
//this marks end of interface 
@end

Important items in code

AppDelegate inherits from UIResponder that handles iOS events
Implements the delegate methods of UIApplication delegate which provide key application events like finished launching, about to terminate and so on.
UIWindow object to manage and co-ordinate the various views on the iOS device screen. It's like the base view over which all other views are loaded. Generally there is only one window for an application.
UIViewController to handle the screen flow.

AppDelegate.m

// Imports the class Appdelegate's interface
import "AppDelegate.h" 

// Imports the viewcontroller to be loaded
#import "ViewController.h" 

// Class definition starts here
@implementation AppDelegate 


// Following method intimates us the application launched  successfully 
- (BOOL)application:(UIApplication *)application 
 didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{
    self.window = [[UIWindow alloc] initWithFrame:
	[[UIScreen mainScreen] bounds]]; 
    // Override point for customization after application launch.
    self.viewController = [[ViewController alloc] 
	 initWithNibName:@"ViewController" bundle:nil];
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
    /* Sent when the application is about to move from active to inactive state.
    This can occur for certain types of temporary interruptions
    (such as an incoming phone call or SMS message)
    or when the user quits the application and it begins the transition to the 
    background state. Use this method to pause ongoing tasks, disable timers, 
    and throttle down OpenGL ES frame rates. Games should use this method 
    to pause the game.*/
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    /* Use this method to release shared resources, save user data, invalidate 
    timers, and store enough application state information	to restore your
    application to its current state in case it is terminated later. If your 
    application supports background execution, this method is called instead 
    of applicationWillTerminate: when the user quits.*/
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    /* Called as part of the transition from the background to the inactive state;
    here you can undo many of the changes made on entering the background.*/
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    /* Restart any tasks that were paused (or not yet started) while the
    application was inactive. If the application was previously in the background, 
	optionally refresh the user interface.*/
}

- (void)applicationWillTerminate:(UIApplication *)application
{
    /* Called when the application is about to terminate. Save data if appropriate.
    See also applicationDidEnterBackground:. */
}

@end

Important items in code

UIApplication delegates defined here. All the methods defined above are UI application delegates and contains no user defined methods.
UIWindow object is allocated to hold the application is allocated
UIViewController is allocated made as window's initial view controller.
To make window visible makeKeyAndVisible method is called.

ViewController.h

#import  

// Interface for class ViewController
@interface ViewController : UIViewController 

@end

Important items in code

The ViewController class inherits the UIViewController which provides the fundamental view management model for the iOS applications.

ViewController.m

#import "ViewController.h"

// Category, an extension of ViewController class
@interface ViewController ()

@end

@implementation ViewController  

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Important items in code

Two methods implemented here which are defined in the base class UIViewController
Do initial setup in viewDidLoad which is called after view loads
didReceiveMemoryWarning method is called in case of memory warning.

iOS - Actions and Outlets

Introduction

Actions and outlets in iOS are referred to as ibActions and ibOutlets respectively where ib stands for interface builder. These are related to the UI elements and we will explore them after knowing visually how to implement them.

Steps Involved

1. Let's use our First iPhone Application.

2. Select the ViewController.xib file from the files in the navigator section.

3. Now you can select the UI elements from the library pane in right hand side of our window which is shown below.

4. You can drag and drop UI elements to our view in our interface builder.

5. Let add a Label and Round Rect Button to our view.

6. From the Editor selector button in the workspace toolbar found on the top right corner as shown below.

Select Assistant editor button

7. We will see two windows in our editor area in the center, one is ViewController.xib file and other is ViewController.h

8. Now right click on the label and select, hold and drag new referencing outlet as shown below

9. Now drop in the ViewController.h in between the curly braces. There may be no curly brace please in the file, if so add before doing this. You will find a pop up as shown below.

10. Now type the label name for the outlet, here I have given myTitleLabel. Click connect and the ibOutlet will be complete.

11. Similarly to add an action right click the Round rect button, select touch up inside and drag it below the curly braces

12. Drop it and name it setTitleLabel.

13. Now select ViewController.m file, you'll find a method as shown below.

-(IBAction) setTitleLabel:(id)sender{
}

14. Add a statement as shown below inside the above method.

[myTitleLabel setTitleText:@"Hello"];

15. Now let's run the program by selecting the run button. You will see the following output.

16. Now click the button.

17. The label that we created outlet have been changed by the action on the button.

18. So from the above example we can conclude that IBOutlet creates a reference to the UIElement (here for the UILabel) and similarly the IBAction links the UIButton with a method which is called on the event touch up inside.

19. You can play around with actions by selecting different events while creating the action.

iOS - Delegates

Example for delegate

Let's assume an object A calls object B to perform an action, once the action is complete object A should know that B has completed the task and take necessary action. This is achieved with the help of delegates.

The key concepts in the above example are,

A is delegate object of B
B will have a reference of A
A will implement the delegate methods of B.
B will notify A through the delegate methods.

Steps in creating a delegate

1. First, create a single view application.

2. Then select File -> New -> File...

3. Then select Objective C Class and click Next.

4. Give the name for the class say SampleProtocol with subclass as NSObject as shown below.

5. Then select create.

6. Add a protocol to the SampleProtocol.h file and updated code is as follows.

#import <Foundation/Foundation.h>
// Protocol definition starts here 
@protocol SampleProtocolDelegate <NSObject>
@required
- (void) processCompleted;
@end
// Protocol Definition ends here
@interface SampleProtocol : NSObject

{
   // Delegate to respond back
   id <SampleProtocolDelegate> _delegate; 

}
@property (nonatomic,strong) id delegate;

-(void)startSampleProcess; // Instance method

@end

7. Implement the instance method by updating the SampleProtocol.m file as shown below.


#import "SampleProtocol.h"

@implementation SampleProtocol

-(void)startSampleProcess{
    
    [NSTimer scheduledTimerWithTimeInterval:3.0 target:self.delegate 
	selector:@selector(processCompleted) userInfo:nil repeats:NO];
}
@end

8. Add an UILabel in the ViewController.xib by dragging the label from the object library to UIView as shown below.

9. Create an IBOutlet for the label and name it as myLabel and update the code as follow to adopt SampleProtocolDelegate in ViewController.h


#import <UIKit/UIKit.h>
#import "SampleProtocol.h"

@interface ViewController : UIViewController<SampleProtocolDelegate>
{
    IBOutlet UILabel *myLabel;
}
@end

10. Implement the delegate method, create object for SampleProtocol and call the startSampleProcess method. The Updated ViewController.m file is as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    SampleProtocol *sampleProtocol = [[SampleProtocol alloc]init];
    sampleProtocol.delegate = self;
    [myLabel setText:@"Processing..."];
    [sampleProtocol startSampleProcess];
	// Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Sample protocol delegate
-(void)processCompleted{    
    [myLabel setText:@"Process Completed"];
}


@end

11. We will see an output as follows, initially the label will be processing which gets updated once the delegate method is called by the SampleProtocol object.

iOS - UI Elements

What UI elements are?

UI elements are visual elements that we can see in our abpplications. Some of these elements respond to user interactions such as buttons, text fields and others are informative such as images, labels.

How to add UI elements?

We can add UI elements both in code and with the help of interface builder. Depending on the need we can use either one of them.

Our Focus

We'll be focussing more on adding UI elements through code in our applications. Using interface builder is simple and straight forward, we just need to drag and drop UI elements.

Our Approach

We will create a simple iOS application and use it for explaining some of the UI elements.

Steps

1. Create a Viewbased application as we did in our First iOS application

2. We will be only updating the ViewController.h and ViewController.m files.

3. Then we add a method to our ViewController.m file specific to creating the UI element.

4. We will call this method in our viewDidLoad method.

5. The important lines of code have been explained in the code with single line comment above those lines.

List of UI elements

UI specific elements and their related functionalies are explained below

S.N.	UI specific elements or funtionality
1	Text Fields It is an UI element that enables the app to get user input.
2	Input types - TextFields We can set the type of input that user can give by using the keyboard property of UITextField
3	Buttons It is used for handling user actions.
4	Label It is used for displaying static content.
5	Toolbar It is used if we want to manipulate something based on our current view.
6	Status Bar It displays the key information of device.
7	Navigation Bar It contains the navigation buttons of a navigation controller which is a stack of view controllers which can be pushed and popped.
8	Tab bar It generally used to switch between various subtasks, views or models within the same view.
9	Image View It is used to display a simple image or sequence of images.
10	Scroll View It is used to display content that is more than the area of screen.
11	Table View It is used for displaying scrollable list of data in multiple rows and sections.
12	Split View It is used for displaying a two panes with master pane controlling information on detail pane.
13	Text View It is used for diplaying scrollable list of text information that is optionally editable.
14	View Transition It explains the various view transitions between views.
15	Pickers It is used for displaying for selecting a specific data from a list.
16	Switches It is used as disable and enable for actions.
17	Sliders It is used to allow users to make adjustments to a value or process throughout a range of allowed values.
18	Alerts It is used to give important information to user.
19	Icons It is an image representation used for an action or depict something related to the application.

iOS - Accelerometer

Introduction

Accelerometer is used for detecting the changes in the position of the device in the three directions x, y and z. We can know the current position of the device relative to ground. For testing this example you'll need it run it on device and it doesn't work on simulator.

Steps Involved

1. Create a simple View based application.

2. Add three labels in ViewController.xib and create ibOutlets naming them as xlabel, ylabel and zlabel.

3. Update ViewController.h as follows.

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIAccelerometerDelegate>
{
    IBOutlet UILabel *xlabel;
    IBOutlet UILabel *ylabel;
    IBOutlet UILabel *zlabel;

}
@end

4. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[UIAccelerometer sharedAccelerometer]setDelegate:self];
    //Do any additional setup after loading the view,typically from a nib
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:
  (UIAcceleration *)acceleration{
    [xlabel setText:[NSString stringWithFormat:@"%f",acceleration.x]];
    [ylabel setText:[NSString stringWithFormat:@"%f",acceleration.y]];
    [zlabel setText:[NSString stringWithFormat:@"%f",acceleration.z]];
}

@end

Output

Now when we run the application in iPhone device we'll get the following output.

iOS - Universal Applications

Introduction

Universal application is the application that is designed for both iPhone and iPad in a single binary. This helps in code reuse and helps in making updates faster.

Steps Involved

1. Create a simple View based application.

2. Change the File name ViewController.xib file to ViewController_iPhone.xib as shown below in the file inspector in the right hand side.

3. Select File -> New -> File... then select the subsection "User Interface" and select View. Click Next.

4. Now select the device family as iPad and click next.

5. Save the file as ViewController_iPad.xib and select Create.

6. Add a label in center of screen in both ViewController_iPhone.xib and ViewController_iPad.xib.

7. Now in ViewController_iPad.xib select the identity inspector and set the custom class asViewController.

8. Update the application:DidFinishLaunching:withOptions method in AppDelegate.m as follows

- (BOOL)application:(UIApplication *)application
  didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
   self.window = [[UIWindow alloc] initWithFrame:[[UIScreen 
   mainScreen] bounds]];
   // Override point for customization after application launch.
   if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        self.viewController = [[ViewController alloc] 
        initWithNibName:@"ViewController_iPhone" bundle:nil];
   }
   else{
        self.viewController = [[ViewController alloc] initWithNibName:
        @"ViewController_iPad" bundle:nil];
   }
   self.window.rootViewController = self.viewController;
   [self.window makeKeyAndVisible];
   return YES;
}

9. Update the devices in project summary to Universal as shown below.

Output

Now when we run the application we'll get the following output.

When we run the application in iPad simulator we'll get the following output.

iOS - Camera Management

Introduction

Camera is one of the common features of mobile devices. It is possible for us to take pictures with the camera and use it in our application and it is quite simple too.

Steps Involved

1. Create a simple View based application.

2. Add a button in ViewController.xib and create IBAction for the button.

3. Add an image view and create IBOutlet naming it as imageView.

4. Update ViewController.h as follows.

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIImagePickerControllerDelegate>
{   
   UIImagePickerController *imagePicker;
   IBOutlet UIImageView *imageView;    
}
- (IBAction)showCamera:(id)sender;

@end

5. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)showCamera:(id)sender {
    imagePicker.allowsEditing = YES;
    if ([UIImagePickerController isSourceTypeAvailable:
        UIImagePickerControllerSourceTypeCamera])
    {
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
    }
    else{
        imagePicker.sourceType = 
        UIImagePickerControllerSourceTypePhotoLibrary;
    }
    [self presentModalViewController:imagePicker animated:YES];

}
-(void)imagePickerController:(UIImagePickerController *)picker 
  didFinishPickingMediaWithInfo:(NSDictionary *)info{
    UIImage *image = [info objectForKey:UIImagePickerControllerEditedImage];
    if (image == nil) {    
        image = [info objectForKey:UIImagePickerControllerOriginalImage];
    }
    imageView.image = image;
    
}

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [self dismissModalViewControllerAnimated:YES];
}

@end

Output

Now when we run the application and click show camera button we'll get the following output.

Once we take picture we can edit the picture i.e. move and scale as shown below.

iOS - Location Handling

Introduction

In iOS we can easily locate the user's current location provided the user allows the application to access the information with the help of core location framework.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add CoreLocation.framework as shown below.

3. Add two labels in ViewController.xib and create ibOutlets naming the labels as latitudeLabel andlongitudeLabel respectively.

4. Now create a new file by selecting File-> New -> File... -> select Objective C class and click next

5. Name the class as LocationHandler with "sub class of" as NSObject.

6. Select create.

7. Now update the LocationHandler.h as follows

#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>

@protocol LocationHandlerDelegate <NSObject>

@required
-(void) didUpdateToLocation:(CLLocation*)newLocation 
 fromLocation:(CLLocation*)oldLocation;
@end

@interface LocationHandler : NSObject<CLLocationManagerDelegate>
{
    CLLocationManager *locationManager;
}
@property(nonatomic,strong) id<LocationHandlerDelegate> delegate;

+(id)getSharedInstance;
-(void)startUpdating;
-(void) stopUpdating;

@end

8. Now update the LocationHandler.m as follows

#import "LocationHandler.h"
static LocationHandler *DefaultManager = nil;

@interface LocationHandler()

-(void)initiate;

@end

@implementation LocationHandler

+(id)getSharedInstance{
    if (!DefaultManager) {
        DefaultManager = [[self allocWithZone:NULL]init];
        [DefaultManager initiate];
    }
    return DefaultManager;
}
-(void)initiate{
    locationManager = [[CLLocationManager alloc]init];
    locationManager.delegate = self;
}

-(void)startUpdating{
    [locationManager startUpdatingLocation];
}

-(void) stopUpdating{
    [locationManager stopUpdatingLocation];
}
-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:
 (CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{
    if ([self.delegate respondsToSelector:@selector
    (didUpdateToLocation:fromLocation:)]) 
    {
        [self.delegate didUpdateToLocation:oldLocation 
        fromLocation:newLocation];

    }
}

@end

9. Update ViewController.h as follows where we have implemented the LocationHandler delegateand create two ibOutlets.

#import <UIKit/UIKit.h>
#import "LocationHandler.h"
@interface ViewController : UIViewController<LocationHandlerDelegate>
{
    IBOutlet UILabel *latitudeLabel;
    IBOutlet UILabel *longitudeLabel;
}
@end

10. Update ViewController.m as follows

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[LocationHandler getSharedInstance]setDelegate:self];
    [[LocationHandler getSharedInstance]startUpdating];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)didUpdateToLocation:(CLLocation *)newLocation 
 fromLocation:(CLLocation *)oldLocation{
    [latitudeLabel setText:[NSString stringWithFormat:
    @"Latitude: %f",newLocation.coordinate.latitude]];
    [longitudeLabel setText:[NSString stringWithFormat:
    @"Longitude: %f",newLocation.coordinate.longitude]];

}

@end

Output

Now when we run the application we'll get the following output.

iOS - SQLite Database

Introduction

Sqlite can be used in iOS for handling data. It just uses the sqlite queries which make it easier for those who know sql.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add libsqlite3.dylib library in choose frameworks.

3. Now create a new file by selecting File-> New -> File... -> select Objective C class and click next

4. Name the class as DBManager with "sub class of" as NSObject.

5. Select create.

6. Now update DBManager.h as follows.

#import <Foundation/Foundation.h>
#import <sqlite3.h>

@interface DBManager : NSObject
{
    NSString *databasePath;
}

+(DBManager*)getSharedInstance;
-(BOOL)createDB;
-(BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
-(NSArray*) findByRegisterNumber:(NSString*)registerNumber;

@end

8. Now update DBManager.m as follows

#import "DBManager.h"
static DBManager *sharedInstance = nil;
static sqlite3 *database = nil;
static sqlite3_stmt *statement = nil;

@implementation DBManager

+(DBManager*)getSharedInstance{
    if (!sharedInstance) {
        sharedInstance = [[super allocWithZone:NULL]init];
        [sharedInstance createDB];
    }
    return sharedInstance;
}

-(BOOL)createDB{
    NSString *docsDir;
    NSArray *dirPaths;    
    // Get the documents directory
    dirPaths = NSSearchPathForDirectoriesInDomains
    (NSDocumentDirectory, NSUserDomainMask, YES);    
    docsDir = dirPaths[0];
    // Build the path to the database file
    databasePath = [[NSString alloc] initWithString: 
    [docsDir stringByAppendingPathComponent: @"student.db"]];
    BOOL isSuccess = YES;
    NSFileManager *filemgr = [NSFileManager defaultManager];    
    if ([filemgr fileExistsAtPath: databasePath ] == NO)
    {
        const char *dbpath = [databasePath UTF8String];        
        if (sqlite3_open(dbpath, &database) == SQLITE_OK)
        {
            char *errMsg;
            const char *sql_stmt =
            "create table if not exists studentsDetail (regno integer 
            primary key, name text, department text, year text)";            
            if (sqlite3_exec(database, sql_stmt, NULL, NULL, &errMsg) 
               != SQLITE_OK)
            {
                isSuccess = NO;
                NSLog(@"Failed to create table");
            }
            sqlite3_close(database);
            return  isSuccess;
        }
        else {
            isSuccess = NO;
            NSLog(@"Failed to open/create database");
        }
    }    
    return isSuccess;
}

- (BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {        
        NSString *insertSQL = [NSString stringWithFormat:@"insert into
        studentsDetail (regno,name, department, year) values
        (\"%d\",\"%@\", \"%@\", \"%@\")",[registerNumber integerValue],
        name, department, year];        
        const char *insert_stmt = [insertSQL UTF8String];
        sqlite3_prepare_v2(database, insert_stmt,-1, &statement, NULL);
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
            return YES;
        } 
        else {
            return NO;
        }
        sqlite3_reset(statement);
    }
    return NO;
}

- (NSArray*) findByRegisterNumber:(NSString*)registerNumber
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {
        NSString *querySQL = [NSString stringWithFormat:
        @"select name, department, year from studentsDetail where 
        regno=\"%@\"",registerNumber];        
        const char *query_stmt = [querySQL UTF8String];
        NSMutableArray *resultArray = [[NSMutableArray alloc]init];
        if (sqlite3_prepare_v2(database,
           query_stmt, -1, &statement, NULL) == SQLITE_OK)
        {
            if (sqlite3_step(statement) == SQLITE_ROW)
            {                
                NSString *name = [[NSString alloc] initWithUTF8String:
                 (const char *) sqlite3_column_text(statement, 0)];
                [resultArray addObject:name];
                NSString *department = [[NSString alloc] initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 1)];
                [resultArray addObject:department];
                NSString *year = [[NSString alloc]initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 2)];
                [resultArray addObject:year];
                return resultArray;
            }
            else{
                NSLog(@"Not found");
                return nil;
            }
            sqlite3_reset(statement);
        }
    }
    return nil;
}

8. Update ViewController.xib file as follows.

9. Create IBOutlets for the above text fields.

10. Create IBAction for the above buttons.

11. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import "DBManager.h"

@interface ViewController : UIViewController<UITextFieldDelegate>
{
    IBOutlet UITextField *regNoTextField;
    IBOutlet UITextField *nameTextField;
    IBOutlet UITextField *departmentTextField;
    IBOutlet UITextField *yearTextField;
    IBOutlet UITextField *findByRegisterNumberTextField;
    IBOutlet UIScrollView *myScrollView;
}

-(IBAction)saveData:(id)sender;
-(IBAction)findData:(id)sender;

@end

12. Update ViewController.m is as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)
  nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)saveData:(id)sender{
    BOOL success = NO;
    NSString *alertString = @"Data Insertion failed";
    if (regNoTextField.text.length>0 &&nameTextField.text.length>0 &&
    departmentTextField.text.length>0 &&yearTextField.text.length>0 )
    {
        success = [[DBManager getSharedInstance]saveData:
        regNoTextField.text name:nameTextField.text department:
        departmentTextField.text year:yearTextField.text];
    }
    else{
        alertString = @"Enter all fields";
    }     
    if (success == NO) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        alertString message:nil
        delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }
}

-(IBAction)findData:(id)sender{
    NSArray *data = [[DBManager getSharedInstance]findByRegisterNumber:
    findByRegisterNumberTextField.text];
    if (data == nil) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        @"Data not found" message:nil delegate:nil cancelButtonTitle:
        @"OK" otherButtonTitles:nil];
        [alert show];
        regNoTextField.text = @"";
        nameTextField.text =@"";
        departmentTextField.text = @"";
        yearTextField.text =@"";
    }
    else{
        regNoTextField.text = findByRegisterNumberTextField.text;
        nameTextField.text =[data objectAtIndex:0];
        departmentTextField.text = [data objectAtIndex:1];
        yearTextField.text =[data objectAtIndex:2];
    }
}

#pragma mark - Text field delegate
-(void)textFieldDidBeginEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 200)];
    [myScrollView setContentSize:CGSizeMake(300, 350)];
}
-(void)textFieldDidEndEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 350)];

}
-(BOOL) textFieldShouldReturn:(UITextField *)textField{
    
    [textField resignFirstResponder];
    return YES;
}
@end

Output

Now when we run the application we'll get the following output where we can add and find student details.

iOS - Sending Email

Introduction

We can send email using the Email application of iOS device.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add MessageUI.framework.

3. Add a button in ViewController.xib and create an action for sending email.

4. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <MessageUI/MessageUI.h>

@interface ViewController : UIViewController<MFMailComposeViewControllerDelegate>
{
    MFMailComposeViewController *mailComposer;
}

-(IBAction)sendMail:(id)sender;

@end

4. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];   
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)sendMail:(id)sender{
    mailComposer = [[MFMailComposeViewController alloc]init];
    mailComposer.mailComposeDelegate = self;
    [mailComposer setSubject:@"Test mail"];
    [mailComposer setMessageBody:@"Testing message 
    for the test mail" isHTML:NO];
    [self presentModalViewController:mailComposer animated:YES];
}

#pragma mark - mail compose delegate
-(void)mailComposeController:(MFMailComposeViewController *)controller 
 didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error{
   if (result) {
        NSLog(@"Result : %d",result);
    }
    if (error) {
        NSLog(@"Error : %@",error);
    }
    [self dismissModalViewControllerAnimated:YES];

}

@end

Output

Now when we run the application we'll get the following output.

On clicking send Email we will get the following output.

iOS - Audio & Video

Introduction

Audio and video is quite common in latest devices. It is supported in iOS with the help ofAVFoundation.framework and MediaPlayer.framework respectively.

Steps Involved

1. Create a simple View based application.

2. Select your project file, select targets, and then we should add AVFoundation.framework andMediaPlayer.framework.

3. Add two buttons in ViewController.xib and create an action for playing audio and video respectively.

4. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <MediaPlayer/MediaPlayer.h>

@interface ViewController : UIViewController
{
    AVAudioPlayer *audioPlayer;
    MPMoviePlayerViewController *moviePlayer;
    
}
-(IBAction)playAudio:(id)sender;
-(IBAction)playVideo:(id)sender;
@end

5. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
   [super didReceiveMemoryWarning];
   // Dispose of any resources that can be recreated.
}
-(IBAction)playAudio:(id)sender{
   NSString *path = [[NSBundle mainBundle]
   pathForResource:@"audioTest" ofType:@"mp3"];
   audioPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:
   [NSURL fileURLWithPath:path] error:NULL];
   [audioPlayer play];
}
-(IBAction)playVideo:(id)sender{
   NSString *path = [[NSBundle mainBundle]pathForResource:
   @"videoTest" ofType:@"mov"];
   moviePlayer = [[MPMoviePlayerViewController 
   alloc]initWithContentURL:[NSURL fileURLWithPath:path]];
   [self presentModalViewController:moviePlayer animated:NO];
}
@end

Note

We need to add audio and video files for ensuring that we get the expected output.

Output

Now when we run the application we'll get the following output.

When we click on play video we will get an output as shown below.

When we click play audio you will hear the audio.

iOS - File Handling

Introduction

File handling cannot be explained visually with the application and hence the key methods that are used for handling files are explained below. Please note that the application bundle only has read permission and we wont be able to modify the files. We can anyway modify documents directory of your application.

Methods used in File Handling

The list of the methods used for accessing and manipulating files are listed below. Here we have to replace the FilePath1, FilePath2 and FilePath strings to our required full file paths to get the desired action.

Check if file exists at a path

   NSFileManager *fileManager = [NSFileManager defaultManager];
   //Get documents directory
   NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains
   (NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDirectoryPath = [directoryPaths objectAtIndex:0];
   if ([fileManager fileExistsAtPath:@""]==YES) {
        NSLog(@"File exists");
    }

Comparing two file contents

   if ([fileManager contentsEqualAtPath:@"FilePath1" andPath:@" FilePath2"]) {
      NSLog(@"Same content");
   }

Check if writable, readable and executable

   if ([fileManager isWritableFileAtPath:@"FilePath"]) {
      NSLog(@"isWritable");
   }
   if ([fileManager isReadableFileAtPath:@"FilePath"]) {
      NSLog(@"isReadable");
   }
   if ( [fileManager isExecutableFileAtPath:@"FilePath"]){
      NSLog(@"is Executable");
   }

Move file

   if([fileManager moveItemAtPath:@"FilePath1" 
   toPath:@"FilePath2" error:NULL]){
      NSLog(@"Moved successfully");
   }

Copy file

   if ([fileManager copyItemAtPath:@"FilePath1" 
   toPath:@"FilePath2"  error:NULL]) {
      NSLog(@"Copied successfully");
   }

Remove file

   if ([fileManager removeItemAtPath:@"FilePath" error:NULL]) {
      NSLog(@"Removed successfully");
   }

Read file

   NSData *data = [fileManager contentsAtPath:@"Path"];

Write file

   [fileManager createFileAtPath:@"" contents:data attributes:nil];

iOS - Accessing Maps

Introduction

Maps are always helpful for us to locate places. And maps are integrated to iOS using the MapKit frame work.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add MapKit.framework.

3. We should also add Corelocation.framework

4. Add a MapView to ViewController.xib and create an ibOutlet and name it as mapView.

5. Now create a new file by selecting File-> New -> File... -> select Objective C class and click next

6. Name the class as MapAnnotation with "sub class of" as NSObject.

7. Select create.

8. Now update MapAnnotation.h as follows.

#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>

@interface MapAnnotation : NSObject<MKAnnotation>
@property (nonatomic, strong) NSString *title;
@property (nonatomic, readwrite) CLLocationCoordinate2D coordinate;

- (id)initWithTitle:(NSString *)title andCoordinate:
  (CLLocationCoordinate2D)coordinate2d;

@end

9. Now update MapAnnotation.m as follows

#import "MapAnnotation.h"

@implementation MapAnnotation
-(id)initWithTitle:(NSString *)title andCoordinate:
 (CLLocationCoordinate2D)coordinate2d{    
    self.title = title;
    self.coordinate =coordinate2d;
    return self;
}
@end

11. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import <CoreLocation/CoreLocation.h>
@interface ViewController : UIViewController<MKMapViewDelegate>
{
    MKMapView *mapView;
}
@end

12. Update ViewController.m is as follows.

#import "ViewController.h"
#import "MapAnnotation.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
   [super viewDidLoad];
   mapView = [[MKMapView alloc]initWithFrame:
   CGRectMake(10, 100, 300, 300)];
   mapView.delegate = self;
   mapView.centerCoordinate = CLLocationCoordinate2DMake(37.32, -122.03);
   mapView.mapType = MKMapTypeHybrid;
   CLLocationCoordinate2D location;
   location.latitude = (double) 37.332768;
   location.longitude = (double) -122.030039;
   // Add the annotation to our map view
   MapAnnotation *newAnnotation = [[MapAnnotation alloc]
   initWithTitle:@"Apple Head quaters" andCoordinate:location];
   [mapView addAnnotation:newAnnotation];
   CLLocationCoordinate2D location2;
   location2.latitude = (double) 37.35239;
   location2.longitude = (double) -122.025919;
   MapAnnotation *newAnnotation2 = [[MapAnnotation alloc] 
   initWithTitle:@"Test annotation" andCoordinate:location2];
   [mapView addAnnotation:newAnnotation2];
   [self.view addSubview:mapView];
}
// When a map annotation point is added, zoom to it (1500 range)
- (void)mapView:(MKMapView *)mv didAddAnnotationViews:(NSArray *)views
{
   MKAnnotationView *annotationView = [views objectAtIndex:0];
   id <MKAnnotation> mp = [annotationView annotation];
   MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance
   ([mp coordinate], 1500, 1500);
   [mv setRegion:region animated:YES];
   [mv selectAnnotation:mp animated:YES];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Output

Now when we run the application we'll get the output as shown below.

When we scroll the map up we will get the output as shown below.

iOS - In-App Purchase

Introduction

In-App purchase is used purchase additional content or upgrade features with respect to the application.

Steps Involved

1. In iTunes connect ensure that you have a unique App ID and when we create the application update with the bundle ID and code signing in Xcode with corresponding provisioning profile.

2. Create a new application and update application information. You can know more about this in apple's Add new apps documentation.

3. Add a new product for in-app purchase in Manage In-App Purchase of your application's page.

4. Ensure you setup the bank details for your application. This needs to be setup for In-App purchaseto work. Also create a test user account using Manage Users option in iTunes connect page of your app.

5. The next steps are related to handling code and creating UI for our In-App purchase.

6. Create a single view application and enter the bundle identifier is the identifier specified in iTunes connect.

7. Update the ViewController.xib as shown below.

8. Create IBOutlets for the three labels and the button naming them as productTitleLabel, productDescriptionLabel, productPriceLabel and purchaseButton respectively.

9. Select your project file, then select targets and then add StoreKit.framework.

10. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <StoreKit/StoreKit.h>

@interface ViewController : UIViewController<
SKProductsRequestDelegate,SKPaymentTransactionObserver>
{
    SKProductsRequest *productsRequest;
    NSArray *validProducts;
    UIActivityIndicatorView *activityIndicatorView;
    IBOutlet UILabel *productTitleLabel;
    IBOutlet UILabel *productDescriptionLabel;
    IBOutlet UILabel *productPriceLabel;
    IBOutlet UIButton *purchaseButton;
}
- (void)fetchAvailableProducts;
- (BOOL)canMakePurchases;
- (void)purchaseMyProduct:(SKProduct*)product;
- (IBAction)purchase:(id)sender;

@end

11. Update ViewController.m as follows.

#import "ViewController.h"
#define kTutorialPointProductID 
@"com.tutorialPoints.testApp.testProduct"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Adding activity indicator
    activityIndicatorView = [[UIActivityIndicatorView alloc]
    initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activityIndicatorView.center = self.view.center;
    [activityIndicatorView hidesWhenStopped];
    [self.view addSubview:activityIndicatorView];
    [activityIndicatorView startAnimating];
    //Hide purchase button initially
    purchaseButton.hidden = YES;
    [self fetchAvailableProducts];    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)fetchAvailableProducts{
    NSSet *productIdentifiers = [NSSet 
    setWithObjects:kTutorialPointProductID,nil];
    productsRequest = [[SKProductsRequest alloc] 
    initWithProductIdentifiers:productIdentifiers];
    productsRequest.delegate = self;
    [productsRequest start];
}

- (BOOL)canMakePurchases
{
    return [SKPaymentQueue canMakePayments];
}
- (void)purchaseMyProduct:(SKProduct*)product{
    if ([self canMakePurchases]) {
        SKPayment *payment = [SKPayment paymentWithProduct:product];
        [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
        [[SKPaymentQueue defaultQueue] addPayment:payment];
    }
    else{
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
        @"Purchases are disabled in your device" message:nil delegate:
        self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
        [alertView show];
    }
}
-(IBAction)purchase:(id)sender{
    [self purchaseMyProduct:[validProducts objectAtIndex:0]];
    purchaseButton.enabled = NO; 
}

#pragma mark StoreKit Delegate

-(void)paymentQueue:(SKPaymentQueue *)queue 
 updatedTransactions:(NSArray *)transactions {
    for (SKPaymentTransaction *transaction in transactions) {
        switch (transaction.transactionState) {
            case SKPaymentTransactionStatePurchasing:
                    NSLog(@"Purchasing");
                break;                
            case SKPaymentTransactionStatePurchased:
               if ([transaction.payment.productIdentifier 
                  isEqualToString:kTutorialPointProductID]) {
                   NSLog(@"Purchased ");
                   UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:
                   @"Purchase is completed succesfully" message:nil delegate:
                   self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
                   [alertView show];
                }               
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;                
            case SKPaymentTransactionStateRestored:               
                NSLog(@"Restored ");               
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                break;                
            case SKPaymentTransactionStateFailed:
                NSLog(@"Purchase failed ");
                break;
            default:
                break;
        }
    }
}

-(void)productsRequest:(SKProductsRequest *)request 
 didReceiveResponse:(SKProductsResponse *)response
{
    SKProduct *validProduct = nil;
    int count = [response.products count];
    if (count>0) {
        validProducts = response.products;
        validProduct = [response.products objectAtIndex:0];
        if ([validProduct.productIdentifier 
           isEqualToString:kTutorialPointProductID]) {
            [productTitleLabel setText:[NSString stringWithFormat:
            @"Product Title: %@",validProduct.localizedTitle]];
            [productDescriptionLabel setText:[NSString stringWithFormat:
            @"Product Desc: %@",validProduct.localizedDescription]];
            [productPriceLabel setText:[NSString stringWithFormat:
            @"Product Price: %@",validProduct.price]];           
        }        
    } else {
        UIAlertView *tmp = [[UIAlertView alloc]
                            initWithTitle:@"Not Available"
                            message:@"No products to purchase"
                            delegate:self
                            cancelButtonTitle:nil
                            otherButtonTitles:@"Ok", nil];
        [tmp show];
    }    
    [activityIndicatorView stopAnimating];
    purchaseButton.hidden = NO;
}

@end

Note:

You have to update kTutorialPointProductID to the productID you created for your In-App Purchase. You can add more than one product by updating the productIdentifiers's NSSet in fetchAvailableProducts. Similary handle purchase related actions for product IDs you add.

Output

Now when we run the application we'll get the following output.

Ensure you had logged out of your account in settings screen. On clicking Initiate Purchase select Use Existing Apple ID. Enter your valid test account username and password. You will be shown the following alert in a few seconds.

Once your product is purchased successfully, you will get the following alert. You can relevant code for updating the application features where we show this alert.

iOS - iAd Integration

Introduction

iAd is used for display ads served by the apple server and helps us in earning revenue from the application.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add iAd.framework in choose frameworks.

3. Update ViewController.h as follows.

#import <UIKit/UIKit.h>
#import <iAd/iAd.h>
@interface ViewController : UIViewController<ADBannerViewDelegate>
{
    ADBannerView *bannerView;
}
@end

4. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    bannerView = [[ADBannerView alloc]initWithFrame:
    CGRectMake(0, 0, 320, 50)];
    // Optional to set background color to clear color
    [bannerView setBackgroundColor:[UIColor clearColor]];
    [self.view addSubview: bannerView];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - AdViewDelegates

-(void)bannerView:(ADBannerView *)banner 
 didFailToReceiveAdWithError:(NSError *)error{
    NSLog(@"Error loading");
}

-(void)bannerViewDidLoadAd:(ADBannerView *)banner{
    NSLog(@"Ad loaded");
}
-(void)bannerViewWillLoadAd:(ADBannerView *)banner{
    NSLog(@"Ad will load");
}
-(void)bannerViewActionDidFinish:(ADBannerView *)banner{
    NSLog(@"Ad did finish");

}
@end

Output

Now when we run the application we'll get the following output.

iOS - GameKit

Introduction

Gamekit is framework that provides leader board, achievements and more features to our iOS application. In this tutorial we will be explaining the steps in adding leader board and updating score.

Steps Involved

1. In iTunes connect ensure that you have a unique App ID and when we create the application update with the bundle ID and code signing in Xcode with corresponding provisioning profile.

2. Create a new application and update application information. You can know more about this in apple add new apps documentation.

3. Setup a leader board in Manage Game Center of your application's page where add a single leaderboard and give leaderboard ID and score Type.

4. The next steps are related to handling code and creating UI for our application.

5. Create a single view application and enter the bundle identifier is the identifier specified in iTunes connect.

6. Update the ViewController.xib as shown below.

7. Select your project file, then select targets and then add GameKit.framework.

8. Create IBActions for the buttons we have added.

9. Update the ViewController.h file as follows.

#import <UIKit/UIKit.h>
#import <GameKit/GameKit.h>

@interface ViewController : UIViewController
<GKLeaderboardViewControllerDelegate>

-(IBAction)updateScore:(id)sender;
-(IBAction)showLeaderBoard:(id)sender;

@end

10. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    if([GKLocalPlayer localPlayer].authenticated == NO)
    {
      [[GKLocalPlayer localPlayer] 
      authenticateWithCompletionHandler:^(NSError *error)
      {
         NSLog(@"Error%@",error);
      }];
    }    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (void) updateScore: (int64_t) score 
forLeaderboardID: (NSString*) category
{
    GKScore *scoreObj = [[GKScore alloc]
    initWithCategory:category];
    scoreObj.value = score;
    scoreObj.context = 0;
    [scoreObj reportScoreWithCompletionHandler:^(NSError *error) {
        // Completion code can be added here
        UIAlertView *alert = [[UIAlertView alloc]
        initWithTitle:nil message:@"Score Updated Succesfully" 
        delegate:self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
        [alert show];

    }];
}
-(IBAction)updateScore:(id)sender{
    [self updateScore:200 forLeaderboardID:@"only4programmers"];
}
-(IBAction)showLeaderBoard:(id)sender{
    GKLeaderboardViewController *leaderboardViewController =
    [[GKLeaderboardViewController alloc] init];
    leaderboardViewController.leaderboardDelegate = self;
    [self presentModalViewController:
    leaderboardViewController animated:YES];

}
#pragma mark - Gamekit delegates
- (void)leaderboardViewControllerDidFinish:
(GKLeaderboardViewController *)viewController{
    [self dismissModalViewControllerAnimated:YES];
}

@end

Output

Now when we run the application we'll get the following output.

When we click show leader board we would get a screen similar to the following.

When we click update score, the score will be updated to our leader board and we will get an alert as shown below.

iOS - Storyboards

Introduction

Storyboards are introduced in iOS 5 and when we use storyboards our deployment target should be 5.0 or higher. Storyboards helps us visual create all the screens of the application along with their flow of screens under one interface MainStoryboard.storyboard. It also helps in reducing coding of pushing/presenting view controllers.

Steps Involved

1. Create a single view application and make sure that you select storyboard checkbox while creating the application.

2. Select MainStoryboard.storyboard where you can find single view controller. Now add one more view controller and update the view controllers as shown below.

3. Now let connect both the view controllers. For this right click on the button name "show modal" and drag it to the right view controller in the left side view controller as shown below.

4. Now select modal from the three options displayed as shown below.

5. Update ViewController.h as follows.

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

-(IBAction)done:(UIStoryboardSegue *)seque;

@end

6. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];	
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
-(IBAction)done:(UIStoryboardSegue *)seque{
    [self.navigationController popViewControllerAnimated:YES];
}

@end

7. Select MainStoryboard.storyboard and right click on the Exit button in the right side view controller select done and connect with back button as shown below.

Output

Now when we run the application in iPhone device we'll get the following output.

Now when we select show modal we will get the following output.

iOS - Auto Layouts

Introduction

Auto layouts were introduced in iOS 6.0 and we can support only deployment target of 6.0 and higher. It helps us create interfaces that can be used for multiple orientations and multiple devices.

Goal of our example

We will add two buttons that will be placed a certain distance from the center of screen. We will also try to add a resizable text field that will be placed from a certain distance from above the buttons.

Our Approach

We will add text field and two buttons in code along with their constraints. The constraints of each UI Elements will be created and added to the super view and we will have to disable auto resizing for each of the UI elements we add in order get the desired result.

Steps Involved

1. Create a simple View based application.

2. We will only edit ViewController.m and it is as follows.

#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, strong) UIButton *leftButton;
@property (nonatomic, strong) UIButton *rightButton;
@property (nonatomic, strong) UITextField *textfield;

@end
@implementation ViewController

- (void)viewDidLoad{
    [super viewDidLoad];
    UIView *superview = self.view;
    /*1. Create leftButton and add to our view*/
    self.leftButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.leftButton.translatesAutoresizingMaskIntoConstraints = NO;
    [self.leftButton setTitle:@"LeftButton" forState:UIControlStateNormal];
    [self.view addSubview:self.leftButton];    
    /* 2. Constraint to position LeftButton's X*/
    NSLayoutConstraint *leftButtonXConstraint = [NSLayoutConstraint 
    constraintWithItem:self.leftButton attribute:NSLayoutAttributeCenterX 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:superview attribute:
    NSLayoutAttributeCenterX multiplier:1.0 constant:-60.0f];
    /* 3. Constraint to position LeftButton's Y*/
    NSLayoutConstraint *leftButtonYConstraint = [NSLayoutConstraint 
    constraintWithItem:self.leftButton attribute:NSLayoutAttributeCenterY 
    relatedBy:NSLayoutRelationEqual toItem:superview attribute:
    NSLayoutAttributeCenterY multiplier:1.0f constant:0.0f];   
    /* 4. Add the constraints to button's superview*/
    [superview addConstraints:@[ leftButtonXConstraint,
    leftButtonYConstraint]];    
    /*5. Create rightButton and add to our view*/
    self.rightButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.rightButton.translatesAutoresizingMaskIntoConstraints = NO;
    [self.rightButton setTitle:@"RightButton" forState:UIControlStateNormal];
    [self.view addSubview:self.rightButton];    
    /*6. Constraint to position RightButton's X*/
    NSLayoutConstraint *rightButtonXConstraint = [NSLayoutConstraint 
    constraintWithItem:self.rightButton attribute:NSLayoutAttributeCenterX 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:superview attribute:
    NSLayoutAttributeCenterX multiplier:1.0 constant:60.0f];
    /*7. Constraint to position RightButton's Y*/
    rightButtonXConstraint.priority = UILayoutPriorityDefaultHigh;
    NSLayoutConstraint *centerYMyConstraint = [NSLayoutConstraint 
    constraintWithItem:self.rightButton attribute:NSLayoutAttributeCenterY 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:superview attribute:
    NSLayoutAttributeCenterY multiplier:1.0f constant:0.0f];
    [superview addConstraints:@[centerYMyConstraint,
    rightButtonXConstraint]];
   //8. Add Text field
    self.textfield = [[UITextField alloc]initWithFrame:
    CGRectMake(0, 100, 100, 30)];
    self.textfield.borderStyle = UITextBorderStyleRoundedRect;
    self.textfield.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:self.textfield];
    //9. Text field Constraints
    NSLayoutConstraint *textFieldTopConstraint = [NSLayoutConstraint 
    constraintWithItem:self.textfield attribute:NSLayoutAttributeTop 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:superview 
    attribute:NSLayoutAttributeTop multiplier:1.0 constant:60.0f];
    NSLayoutConstraint *textFieldBottomConstraint = [NSLayoutConstraint 
    constraintWithItem:self.textfield attribute:NSLayoutAttributeTop 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:self.rightButton 
    attribute:NSLayoutAttributeTop multiplier:0.8 constant:-60.0f];
    NSLayoutConstraint *textFieldLeftConstraint = [NSLayoutConstraint 
    constraintWithItem:self.textfield attribute:NSLayoutAttributeLeft 
    relatedBy:NSLayoutRelationEqual toItem:superview attribute:
    NSLayoutAttributeLeft multiplier:1.0 constant:30.0f];
    NSLayoutConstraint *textFieldRightConstraint = [NSLayoutConstraint 
    constraintWithItem:self.textfield attribute:NSLayoutAttributeRight 
    relatedBy:NSLayoutRelationEqual toItem:superview attribute:
    NSLayoutAttributeRight multiplier:1.0 constant:-30.0f];
    [superview addConstraints:@[textFieldBottomConstraint ,
    textFieldLeftConstraint, textFieldRightConstraint, 
    textFieldTopConstraint]];   
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end

What we did here?

In steps marked 1, 5 and 8 we just programmatically add two buttons and a text field respectively. In rest of the steps we create constraints and add those constraints to respective super views which are actually self.view. When you look into the one of the left button's constraint as shown below,

    NSLayoutConstraint *leftButtonXConstraint = [NSLayoutConstraint 
    constraintWithItem:self.leftButton attribute:NSLayoutAttributeCenterX 
    relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:superview attribute:
    NSLayoutAttributeCenterX multiplier:1.0 constant:-60.0f];

We actually have constraintWithItem and toItem which decides between which UI element we are creating the constraint. The attribute decides on what basis the two elements have linked together. Related by decides how much the attributes have effect between the elements. Multiplier is the multiplication factor and constant will be added to the multipler. Here we are saying that X of leftButton is always greater than or equal to -60 pixels with respect to the center of the super view. Similarly other constraints are defined.

Output

Now when we run the application we'll get the following output on iPhone simulator.

When we change the orientation of the simulator to landscape we will get following output.

When we run the same application on iPhone 5 simulator we will get the following output.

When we change the orientation of the simulator to landscape we will get following output.

iOS - Twitter & Facebook

Introduction

Twitter has been integrated to iOS 5.0 and Facebook has been integrated in iOS 6.0. Our tutorial focuses on using the classes provided by apple and the deployment targets for Twitter and Facebook are iOS 5.0 and iOS 6.0 respectively.

Steps Involved

1. Create a simple View based application.

2. Select your project file, then select targets and then add Social.framework andAccounts.framework in choose frameworks

3. Add two buttons named facebookPost , twitterPost and create ibActions for them.

4. Update ViewController.h as follows.

#import <Social/Social.h>
#import <Accounts/Accounts.h>
#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

-(IBAction)twitterPost:(id)sender;
-(IBAction)facebookPost:(id)sender;

@end

4. Update ViewController.m as follows.

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)facebookPost:(id)sender{
   
   SLComposeViewController *controller = [SLComposeViewController 
   composeViewControllerForServiceType:SLServiceTypeFacebook];
   SLComposeViewControllerCompletionHandler myBlock = 
   ^(SLComposeViewControllerResult result){
          if (result == SLComposeViewControllerResultCancelled)
          {                
            NSLog(@"Cancelled");                
          } 
          else                
          {
            NSLog(@"Done");
          }
          [controller dismissViewControllerAnimated:YES completion:nil];
        };
   controller.completionHandler =myBlock;        
   //Adding the Text to the facebook post value from iOS
   [controller setInitialText:@"My test post"];        
   //Adding the URL to the facebook post value from iOS
   [controller addURL:[NSURL URLWithString:@"http://www.test.com"]];        
   //Adding the Text to the facebook post value from iOS
   [self presentViewController:controller animated:YES completion:nil];    
}

-(IBAction)twitterPost:(id)sender{
    SLComposeViewController *tweetSheet = [SLComposeViewController 
    composeViewControllerForServiceType:SLServiceTypeTwitter];
    [tweetSheet setInitialText:@"My test tweet"];
    [self presentModalViewController:tweetSheet animated:YES];
}

@end

Output

Now when we run the application and click facebookPost we will get following output.

When we click twitterPost we will get following output.

iOS - Memory Management

Introduction

Memory management in iOS was initially non ARC(Automatic reference counting) where we have to retain and release the objects. Now it supports ARC where we don't need to add retain and release. Actually the Xcode takes care of the job automatically in compile time.

Problems faced

The two major problems faced as per apple documentation are,

Freeing or overwriting data that is still in use. This causes memory corruption, and typically results in your application crashing, or worse, corrupted user data.

Not freeing data that is no longer in use causes memory leaks. A memory leak is where allocated memory is not freed, even though it is never used again. Leaks cause your application to use ever-increasing amounts of memory, which in turn may result in poor system performance or (in iOS) your application being terminated.

Memory Management rules

We own the objects we create and we have to subsequently release them when they are no longer needed.

Retain can be used t gain ownership of an object that we did not create. We have release these objects too when it's not needed.

Don't release the objects that we don't own.

Handling memory in ARC

You don't need to use release and retain in ARC. So, all the view controller's objects will be released when the view controller is removed. Similarly any objects sub objects will be released when they are released. Remember if other classes have strong reference to an object of the class then the whole class won't be released. So it is recommended to use weak properties for delegates.

Using memory management tools

We can analyze the usage of memory with the help of Xcode tool Instruments. It includes tools like activity monitor, Allocations, leaks, zombies and so on.

Steps for analyzing memory allocations

1. Open an existing application.

2. Select Product and then Profile as shown below.

3. Then select Allocations in the next screen shown below and select Profile.

4. We will see the allocation of memory for different objects as shown below.

5. You can switch between view controllers and check whether the memory is released properly.

6. Similarly instead of Allocations we can use Activity Monitor to see the overall memory allocated for the application and it's shown below.

7. These tools help in knowing how much we use and what the places possible leaks have occurred.

iOS - Application Debugging

Introduction

When we do application we may commit mistakes which can lead to different kinds of errors. So in order to fix these errors or bugs we need to debug the application.

Selecting a Debugger

Xcode has to debuggers namely GDB and LLDB debuggers, and GDB is selected by default. LLDB is a debugger that is part of the LLVM open source compiler project. You can change the debugger by edit active schemes option.

How to find coding mistakes?

We just need to build our application and our code is compiled by compiler and all the messages, errors and warnings with their reason will be displayed and we can correct them. You can click Product and click analyze, you will be given the possible issues in the application.

Set Breakpoints

Break points help us to know the different states of our application objects which help us identifying many flaws including logical issues. We just need to click over the line number to create a breakpoint. We can click and drag it out to remove the break point. An example breakpoint is shown below.

When we run the application and select the playVideo button the application will be paused for us to analyze the states of our application. When breakpoint is triggered we will get an output as shown below.

You can easily identify which thread has triggered the breakpoint. In the bottom you can see objects like self, sender and so on which hold the values of corresponding objects and we can expand some of these objects and see what is the state of each of them.

To continue the application we will select the continue button (left most button) in the debug area shown below. The other options include step in, step out and step over.

Exception breakpoint

We also have exception breakpoint that triggers application to stop in location where the exception occurs. We can create exception breakpoint by selecting the + button after selecting the debug navigator. You will get the following window.

Then we need to select Add Exception Breakpoint which will show the following window.

iOS

iOS (iPhone, iPad) Tutorial

iOS - Getting Started

General Overview

Registering as an Apple developer

Apple iOS Developer Program

iOS - Environment Setup

iOS - Xcode Installation

Interface Builder

iOS simulator

iOS - Objective C

Introduction

Interface and Implementation

Object Creation

Methods

Class method

Instance methods

Important data types in Objective C

Printing logs

Control Structures

Properties

Accessing Properties

Categories

Arrays

Dictionary

iOS - First iPhone Application

Creating our First App

Digging deep into the code of the First iOS application

AppDelegate.h

Important items in code

AppDelegate.m

Important items in code

ViewController.h

Important items in code

ViewController.m

Important items in code

iOS - Actions and Outlets

Introduction

Steps Involved

iOS - Delegates

Example for delegate

Steps in creating a delegate

iOS - UI Elements

What UI elements are?

How to add UI elements?

Our Focus

Our Approach

Steps

List of UI elements

iOS - Accelerometer

Introduction

Steps Involved

Output

iOS - Universal Applications

Introduction

Steps Involved

Output

iOS - Camera Management

Introduction

Steps Involved

Output

iOS - Location Handling

Introduction

Steps Involved

Output

iOS - SQLite Database

Introduction

Steps Involved

Output

Introduction

Steps Involved

Output

iOS - Audio & Video

Introduction

Steps Involved

Note

Output

iOS - File Handling

Introduction

Methods used in File Handling

Now when we run the application we'll get the output as shown below.

When we scroll the map up we will get the output as shown below.

Now when we run the application we'll get the following output.

When we click show leader board we would get a screen similar to the following.

When we click update score, the score will be updated to our leader board and we will get an alert as shown below.

Now when we run the application in iPhone device we'll get the following output.

Now when we select show modal we will get the following output.