ios development

iOS Development

Md. Shakil AhmedSoftware Engineer Astha it research & consultancy ltd.Dhaka, Bangladesh

16th October 2011

Introduction

Topic Focus:- What is iOS & iOS Development?- iOS Dvelopment tools- Creating a new iOS application.- Getting Familiar with Xcode and iOS SDK- Delegate - Objective C- Memory Management- Crash Reports- iPhone frameworks

What is iOS & iOS Development?

• iOS stands for iPhone Operating System• iOS made for iPhone, iPod Touch & iPad• iOS development is developing applications

for iOS Devices.

iOS Application

There is three ways to do mobile applications• Mobile Web Interface • Develop by Flash• Develop by the native platform

Mobile Web Applications

• This application is mostly connected, so most of the time user can’t handle it without internet or cached history

• Javascript provides reach function to access some hardware like GPS and other devices specific hardware

• Developer doesn’t have much authority over the device, tied by the browser.

Flash

• Can be used if the application is all about interface

• currently flash can be used to act like real application, it has access to camera, GPS... Etc

• Performance in not good like the native platform.

Native Applications

• You can do what ever you want to do, except what the framework doesn’t allow you to do.

Smartphone OS Market Share, Q4 2010

Needed to develop for iPhone

• Knowledge of Objective C• Mac OS X Intel based machine• iPhone Development tools• iPhone or iPod touch

iPhone Development tools

• Xcode

Create New Application

1. Open Xcode.2. Select File→New Project.3. In the dialog that opens, select iPhone OS, then

View-Based Application and click Choose.4. Name the project “HelloWorld” and click Save.5. At this point, you can build and run (click the

Build and Go icon in the toolbar). The HelloWorld application shows only a blank gray screen when run in the Simulator.

Create New Application

Xcode

Xcode

• Compiled Code -> your's and framework's

• Nib – files: UI--‐elements

• Resources: images, sounds.

• Info.plist – file: app configuraIon

info.plist

Info.plist in Xcode

nib-- file?‐

• Interface Builder is used for creating Uis• The interface is stored in a file .n/xib

– .nib = Next Interface Builder– .xib = new version (Interface Builder 3) of nib

• The xib file is xml!

nib-- file‐

Nib – files in Interface Builder

icons and images

Life Cycle

Design Pattern: Delegate

• Xcode project template has provided UIApplicaIonDelegate for you

• Can implement:- applicationDidFinishLaunching- applicationWillTerminate– applicationDidReceiveMemoryWarning

• One object sends periodically messages to another object specified as its delegate

Delegate#import <UIKit/UIKit.h>@interface HelloWorldAppDelegate : NSObject

<UIApplicationDelegate> {UIWindow *window;UITextField *mytextfield;}@property (nonatomic, retain) IBOutlet UIWindow *window;@property (nonatomic, retain) IBOutlet UITextField

*mytextfield;- (IBAction) userClicked: (id) sender;@end

Delegate

• nonatomic - single threaded application• retain - memory management• IBOutlet - variables to attach to Interface

Builder objects• IBAction - methods to attach to Interface

Builder actions

In Interface Builder

Delegate classes implementation#import "HelloWorldAppDelegate.h"@implementation HelloWorldAppDelegate@synthesize window;@synthesize mytextfield;- (IBAction) userClicked: (id) sender{NSString* text = [mytextfield text];UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Hello“

message:text delegate:nil cancelButtonTitle:@"Ok“ otherButtonTitles:nil];

[alert show];[alert release];}

Delegate classes implementation- (void)applicationDidFinishLaunching:(UIApplication

*)application {// Override point for customization after application

launch[window makeKeyAndVisible];}- (void)dealloc {[window release];[super dealloc];}@end

Result

Objective C

• You can consider it Extension for C language• ObjC add more dynamicity to C Language• Single inheritance from super class and

protocols is used as interfaces• Totally new syntax but still can use C with it.

Objective C

New concepts– Class definition– Protocol implementation– Class messages– Many more …

Classes and Objects

• Classes declare the state and behavior• State (class data) is instance variables• Behavior is methods

Class and instance methods

• Instances responds to “Instance methods”1. -(id)init;2. -(char*)getName;

• Class responds to “Static methods”1. +(id)alloc;2. +(char*)getClassName;

Message syntax (calling methods)

• Function calling in Objective C called message, this is to give more dynamicity to the language, some times if the method is not implemented the calling result will be nil = null– [objectOfClass functionName];– [objectOfClass functionName:Arg1];

• Calling staic method– [Class functionName];– [Class functionName:Arg1];

Objective C

• Dot Syntax– It is only working in Objective C 2.0– It is only used for properties of object

• Dynamic Casting – Using type “id” , id is pointer to void “C Style

void*”– id object = [Class new];

• Static casting– Class* object = [Class new];

Objective C• nil is equivalents to null • Objective C Class has no operators overloading• Objective C Class has no constructors or destructors• Boolean type is, BOOL

– YES is TRUE– NO is FALSE

Memory Management

Rules :You only release or autorelease objects you

own.• If you own the object by alloc, copy or retain,

you have to release or autorelease• If the object is not owned by you, don’t call

release or autorelease

Memory Management

Memory Management

Local Variable• Always release or autorelease in the same

scope

Crash Reports

Crash Types

• EXC_BAD_ACCESS (SIGBUS or SIGSEGV)• EXC_CRASH (SIGABRT)• Low Memory• 00000020

iPhone frameworks• Foundation • UIKit• CoreGrphics• CFNetwork• CoreLocation• CoreData• ExternalAccessory• GameKit

MapKit

IOKit

MediaPlayer

AddressBook

MobileCoreSerivces

OpenGL

Security

StoreKit

And many more

CoreData

Core Location & MapKit

Multitasking

• Available in iOS 4.

iPhone Development

• It is true that Objective C is not as strong as any other language but the huge coverage of frameworks that is provided by Apple makes it Ok to use such SDK.

Thanks!