Bootstrapping iPhone Development

Munjal Budhabhatti Senior Consultant

Sep/24/2009 San Antonio

Agenda

!!Current state of iPhone Development

!!Fast track to Objective – C

!!Fast track to XCode and Interface Builder

!!Getting productive using OR-Framework, Testing,

Serialization

Current state of iPhone Development

•! Requirements

–! Intel based Mac with OSX 10.5

–! iPhone SDK (Sign-up for iPhone Developer Program $99 for a year)

–! Do NOT need iPhone or iPod Touch (Work on iPhone Simulator)

•! Developer Resources

http://developer.apple.com/iphone

http://devforums.apple.com

http://cs193p.stanford.edu

Fast track to Objective – C

•! Object oriented programming language to write Applications for iPhone and Mac OS

•! Powerful set of extensions to the standard ANSI C language

–! Object oriented

–! Dynamic (Adds Smalltalk-style or Ruby-style messaging)

•! You manage your memory – Probably a good thing in mobile devices

Objective – C Syntax

•! Objective – C is a strict superset thin layer on top of ANSI C

•! Compile any ANSI C program with Objective – C compiler

•! Object syntax derived from Smalltalk

•! Non object oriented syntax identical to C

•! A bit clumsy syntax. Can get lost in the woods. Do NOT let the syntax

defeat you.

Coding in Objective – C

•! Classes are developed using a header and an implementation.

•! Names and types of instance variables and method signature in

header file. Implement methods in implementation file

Interface

@interface classname : superclassname { //instance variables

} +classMethod1; +(returnType) classMethod2; -instanceMethod1; -(returnType) instanceMethod2;

@end

Implementation

@implementation classname + classMethod1 { } + (returnType) classMethod2 { } - instanceMethod1 { } - (returnType) instanceMethod2 { }

Messages (Methods) in Objective – C

•! Java and C# implements Simula-style programming model: a method

is bound to section of code in a compiler

•! Objective – C is based on sending messages to object instances.

Message is simply a name, resolved at runtime by the receiving object.

•! fullName = [firstName stringByAppendingString: lastName]

•! No type-checking. If the object cannot respond to a message it simply

ignores it. No NULL checking!! Yay!!

Static and Dynamic Typing Objective – C

•! Static typing using NSObject – the mother of almost all objects. You

can have objects that don’t derive from NSObject.

•! Dynamic typing using id

–! Sending messages to Nil is OK

–! Dynamic objection creation: objc_getClass, class_createInstance,

class_getInstanceMethod, class_getInstanceVariable

–! TypeIntrospection : isMemberOfClass & isKindOfClass

Invocation and Memory Management in Objective – C

•! Memory management possible using Garbage collector for Mac OS

•! You manage your memory for iPhone OS

•! LeanManager *ronCampbell = [[LeanManager alloc] init];

Protocols in Objective – C

•! Supports multiple-inheritance of specification

•! Similar to Interface in C# and Java. However, the methods could be

optional.

•! Used to declare methods that could be implemented by any class

•! Used to declare interface to an object while concealing its class

•! Used to capture similarities among classes that are not in hierarchy

Protocol Example in Objective – C

@protocol Serialization - (void) serialize; - (void) deserialize;

@end

@interface AccountImage : Image <Serialization> - (void) serialize; - (void) deserialize;

@end

Forwarding in Objective – C

•! Dynamic nature of Objective C allows forwarding of messages

•! If an object doesn’t respond to a message, it can forward to one that

probably could.

•! Similar to method_missing in Ruby

•! ages = [persons age]

Category in Objective – C

•! A category allows you to add methods to an existing class – even for

ones that you don’t own or have the source code

•! Allows to extend the functionality without subclassing

•! Split the implementation of your class between several files

•! Caveat: Cannot create new instance variable in a class

Fast track to Interface Builder

•! App for iPhone devs to create GUI

•! Typical MVC pattern. Write models and controllers in Xcode. Build

interface in Interface Builder

•! One could build interface using code. However, I would advise to bear

the pain once and learn using Interface Builder with Xcode.

•! Nib file and the magic

Fast Track to OR-framework such as Active Record

•! Beautify your models

–! Will you make raw SQL calls ?

•! Start using ObjectPersistentFramework

Fast track to Testing

•! Test using GoogleToolbox

•! Mock using OCMock

•! Serialization using JSON framework for iPhone

iPhone development fundamentals

•! Cocoa Touch – Framework to develop touchscreen applications: UI

elements, event dispatching, application lifecycle

•! Media – Graphics, animations, sound, video

•! Core Services – Collections, Strings, Location, SQLLite, Networking

•! Core OS Layer – Standard IO/, Power Management

main() method

•! Java/C# developers look for “main()” method

•! NSApplication provides the central framwork for app execution

•! Every app creates one instance of NSApplication in main()

•! After NSApplication creation, load the Nib file and start event loop

•! Nib file loads the UI

•! applicationDidFinishLauching() method called when app is launched

View Controllers

•! Model View Controller Pattern

•! Each view in an iPhone app is managed by UIViewController

•! Mother of all view classes

•! Importance of IBAction and IBOutlet

•! IBAction: editButtonClicked()

•! IBOutlet: UILabel

Table View Controller

•! Define and populate NSMutableArray in initWithCoder

•! Implement numberOfRowsInSection protocol for tabelView

•! Implement cellForRowAtIndexPath

•! Improve performance by reusing cells

Navigation Controller

•! Mail app is the best way to understand navigation controller

•! Navigation controller maintains stack of view controllers

•! Each controller represents one node in hierarchy

•! Typical push and pop to manage controllers

•! [self.navigationController pushViewController: self.ctr animate:YES]

•! [self.navigationController popViewControllerAnimate: YES];

File I/O

•! Your appliction is Sandboxed. Cannot access data from other apps

•! Documents directory

•! Tmp directory