iOS Development

Lots of market share

Java

Manufacturer control of OS

version

Large range of device spec

Declining popularity

Poor device performance

Accesible by any device

Limited APIs

Poor performance

iOS70% of all smartphones sold by Verizon and AT&T were

iPhones 1

90% of all mobile purchases are iPhones or iPads 2

Apple controls the market with 90% of all tablets sold being iPads 3

RequirementsApple computer (Mac)

$100/yr Personal Developer Account

OSX 10.7+ for iOS 5.0+

iOS device to test on

Basics of iOS

C

C++

Languages

Objective - C

Languages

UI framework for iPhone, iPod, and iPad

Cocoa Touch

Core Animation

Multitasking

Gesture Recognition

Cocoa Touch

UIKit Objects

NS* Objects

Cocoa Touch

3D

Low level

C or C++

OpenGL ES

Best Practices

Functions

In Objective - C, what we normally refer to as "functions" are now called messages. I usually call them "methods" because it encompasses both meanings.

Functions

In Objective - C, what we normally refer to as "functions" are now called messages. I usually call them "methods" because it encompasses both meanings.

Messages are declared and defined similar to functions

-(void)imageLoader:(NSString*)url;

Functions

In Objective - C, what we normally refer to as "functions" are now called messages. I usually call them "methods" because it encompasses both meanings.

Messages are declared and defined similar to functions

-(void)imageLoader:(NSString*)url;

Return type

Functions

In Objective - C, what we normally refer to as "functions" are now called messages. I usually call them "methods" because it encompasses both meanings.

Messages are declared and defined similar to functions

-(void)imageLoader:(NSString*)url;

Return type Name

Functions

In Objective - C, what we normally refer to as "functions" are now called messages. I usually call them "methods" because it encompasses both meanings.

Messages are declared and defined similar to functions

-(void)imageLoader:(NSString*)url;

Return type Name ParametersSeparated by ":"

Classes

Interface

Definitions of:● Methods● Private variables● Public variables● Delegates

Implementation

Does all of the work

Subclassing

You can subclass ALL of the UIKit and NS* objects

Highly recommend making your own objects if you are ever making a lot of custom methods

UIKit Hierarchy

Anatomy of a class

Interface

InterfaceClass

InterfaceClass

Private variables

InterfaceClass

Private variables

Public variables

InterfaceClass

Private variables

Public variables

Instance methods

InterfaceClass

Private variables

Public variables

Instance methods

Delegate

InterfaceClass

Private variables

Public variables

Instance methods

Delegate methods

Delegate

@propertyWhen an object is declared with @property, you must then use @synthesize in the implementation of your class.

@propertyWhen an object is declared with @property, you must then use @synthesize in the implementation of your class.

@synthesize creates GETTERs and SETTERs for the object

@propertyWhen an object is declared with @property, you must then use @synthesize in the implementation of your class.

@synthesize creates GETTERs and SETTERs for the object

Define the retention of the object in its @property definition. We'll talk about this later.

Implementation

Basic structure:

@synthesizeMethods

Deallocating

Delegates

Delegate Example@interface ImageLoader : NSObject

● Loads an image asynchronously● Sends a message �to its delegate when loaded● Declares method -(void)imageDidLoad

Delegate Example@interface ImageLoader : NSObject

● Loads an image asynchronously● Sends a message �to its delegate when loaded● Declares method -(void)imageDidLoad

@interface MyTableView : UITableViewController● Requests and loads data● Creates ImageLoader objects to load images async.● Is the ImageLoader object's delegate

Delegate ExampleInside MyTableView.m

ImageLoader *imgLoader = [[ImageLoader alloc] init];imgLoader.delegate = self;

Delegate ExampleInside MyTableView.m

ImageLoader *imgLoader = [[ImageLoader alloc] init];imgLoader.delegate = self;

...

-(void)imageDidLoad{ ...}

Delegate Example

MyTableView instantiates ImageLoaderImageLoader owns method -(void)imageDidLoad

Delegate Example

MyTableView instantiates ImageLoaderImageLoader owns method -(void)imageDidLoad

BUT

ImageLoader sends message imageDidLoad to MyTableView

Delegate Example

MyTableView instantiates ImageLoaderImageLoader owns method -(void)imageDidLoad

BUT

ImageLoader sends message imageDidLoad to MyTableView

BUT

MyTableView defines what -(void)imageDidLoad does

In many instances, a class will be its own delegate, e.g.:

A UITableViewController will be its own delegate to respond to table cell touches and scrolling

Memory Management

Device Memory

In developing apps, we have to bear in mind that we are working with very limited memory

512MB in most cases

Should develop to use at most half of that

Springboard uses lots of memory

PointersAll UI* and NS* objects are declared as pointers

PointersAll UI* and NS* objects are declared as pointers

NSArray *arr = [[NSArray alloc] init];

PointersAll UI* and NS* objects are declared as pointers

NSArray *arr = [[NSArray alloc] init];

Object

PointersAll UI* and NS* objects are declared as pointers

NSArray *arr = [[NSArray alloc] init];

Object AllocateMemory

PointersAll UI* and NS* objects are declared as pointers

NSArray *arr = [[NSArray alloc] init];

Object AllocateMemory

Initialization

PointersPointers have different states

retain, atomic, assign, copy, readonly, readwrite, strong

We should only really worry about retaining objects

PointersIf an object is retained, IT MUST BE RELEASED

If an object is instantiated is retained, it is the responsibility for the object's creator release it from memory or else it will remain in memory, causing a leak.

PointersIf an object is retained, IT MUST BE RELEASED

If an object is instantiated is retained, it is the responsibility for the object's creator release it from memory or else it will remain in memory, causing a leak.

Smaller objects won't cause big issues, but objects containing images or files will.

PointersIn iOS 5.0+ Apple introduced Automatic Reference Counting (ARM) which is a simple garbage collector (memory manager).

ARM manages objects and releases them.

PointersIn iOS 5.0+ Apple introduced Automatic Reference Counting (ARM) which is a simple garbage collector (memory manager).

ARM manages objects and releases them.

Limits your apps to iOS 5.0+ devices!

FrameworksHundreds of Open Source and paid frameworks for games, boilerplates, extensions, etc.

FrameworksHundreds of Open Source and paid frameworks for games, boilerplates, extensions, etc.

Apple prohibits the use of third-party libraries. Anything you use or create must be uncompiled.

Contact

Ryan Nystrom

937.367.8939

rnystrom@whoisryannystrom.com

More ResourcesProgramming iOS 5

O'Reilly Bookshttp://goo.gl/9LY6P

Apple's DocumentationXcode Docs

Sources

http://thenextweb.com/apple/2012/01/26/crazy-81-of-all-smartphones-sold-by-att-in-q4-were-iphones/1

http://gigaom.com/apple/study-apples-iphone-ipad-account-for-90-percent-of-mobile-purchases/2

http://daringfireball.net/2011/11/fun_with_numbers3