ios development
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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!
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