iPhone 101

Outline

Objective-C Random bits of the API Using the simulator Debugging with Xcode

Objective-C

Superset of 'C' with OO stuff added C++ classes → interface/implementation C++ methods → messages No static member variables Only need to declare public methods or

those needed before the implementation Inheritance with Java-like multiple

inheritance (using protocols)

Objective-C

File extensions: .h, .m, and .mm Class definition:

@interface StringParser : NSObject {@private

NSString* fContent;}

- (id)init:(NSString *)content options:(int)options;+ (int)SomeStaticMethod:(int)value;

@end

Objective-C#import “StringParser.h”

@implementation StringParser

- (id)init:(NSString *)content options:(int)options{

fContent = [content retain];return self;

}

- (void)dealloc{

[fContent release];[super dealloc];

}

+ (int)SomeStaticMethod:(int)value { }

@end

More Objective-C

Object allocation, destruction and reference counting using retain/release/autorelease

Categories Properties Delegate objects using @protocols

More Objective-C Most Objective-C methods return the object itself

(as an 'id') so you can chain calls in a single statement.

/* nested brackets */bb = [[[UIBarButtonItem alloc] initWithCustomView:logo] autorelease];

NSArray *paths = SomeFunction();NSString *downloadPath = [[[paths objectAtIndex:0]

stringByAppendingPathComponent:kDownloadFolder] retain];

More Objective-C (categories)/* declaring categories */@interface NSString (NSString_URLEncode)- (NSString *) encodeAsURL;@end

@implementation NSString (NSString_URLEncode)

- (NSString *) encodeAsURL{

/* do stuff using public methods of NSString */}

@end

/* using the category */NSString *foo = SomeFunctionThatReturnsAString();[request open:@”GET” url:[foo encodeAsURL]];

More Objective-C (properties)/* in class definition */@private

NSObject<RequestManagerDelegate> *delegate;NSString *fName;

/* in method area (after) */@property(assign) NSObject<RequestManagerDelegate>* delegate;@property(nonatomic, retain) name;

/* implementation */@synthesize delegate;@synthesize name = fName;

/* accessing */Foo *foo = [[foo alloc] init];foo.delegate = self;foo.name = @”bar”;

More Objective-C (delegates)/* protocol declaration */@protocol RequestManagerDelegate- (void)onLoginComplete:(YYLoginStatus)status msg:(NSString *)msg;@end

/* class which has a delegate object */NSObject<RequestManagerDelegate> *delegate;

/* Calling a delegate method */[delegate onLoginComplete:kNetworkError msg:nil];

/* class that implements the delegate methods */@interface SomeClass : BaseClass <RequestManagerDelegate>@end

/* delegate method implementation */#pragma mark RequestManager delegate methods

- (void)onLoginComplete:(YYLoginStatus)status msg:(NSString *)msg{ }

Cocoa Touch API

Data types: id, BOOL, NSInteger, NSUInteger, NSNumber, NSString, long long

Collections: NSDictionary, NSArray, NSSet and their mutable friends

NSTimer, NSThread*, NSURLConnection UIResponder for managing the responder

chain and touch events Core Graphics, Core Animation, Core Audio,

Core Location*Note: @synchronized (obj) can be used by multi-threaded apps

Anatomy of an iPhone app

App delegate: lifecycle (ex: applicationDidFinishLaunching, applicationWillTerminate)

Navigation bar, tab bar, and view controllers Event driven using a “run loop” (provided for

main thread) Register “selectors” to handle events: syntax:

@selector(methodName:arg1:arg2:) Implement delegate protocols to handle events

from various UI/data objects

Anatomy of an iPhone app

UI construction – code or Interface builder UIKit is the iPhone UI framework UIViewController for managing screens UI elements: UIView, UIImageView,

UIButton, UIPickerView, UILabel, UITextView, UITableView, UIAlertView, etc.

Some UIView useful methods: addSubview and removeFromSuperview beginAnimations:context: method and

transform property for simple implicit animation

Anatomy of an iPhone app

UINavigationBar / Item UIBarButtonItem UIImageView / UIImage UILabel UITextField UIButton UITabBarController UITabBarItem/badgeValue

Tab bar components

Navigation item components

UICatalog sample app

iPhone SDK miscellany

retain/release/autorelease carefully! SDK class factory functions usually return

autorelease'd objects (ex: [NSString stringWithFormat...])

A view-controller's loadView can get called multiple times if the view is released due to low memory

Localizing strings using NSLocalizedString User-defined “OTHER_CFLAGS” for build

flags

Workshop - A simple tab-bar based iPhone app

1.Enable code in applicationDidFinishLaunching to add one view controller

2.In FirstViewController, add a red box at 10,10 which is 100x100 using UIView::initWithFrame and CGRectMake()

3.Add a white label in that box at 10,10 with a 12pt system font

4.Add a second view controller and give it a yellow background

5.Add names and tab bar images (UITabBarSystemItem) to both view controllers

6.Inspect code for memory leaks. Did you remember to release after adding views to subviews?

7.In the second view controller, use a timer (NSTimer scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:) with 1 second interval to increment a counter (an instance of UILabel) somewhere in the middle of the screen. Use NSString::stringWithFormat to convert a number to a string printf-style.

8.Use Xcode to set breakpoints and inspect variables