OS X Development Tom Schroeder

Table of Contents Who cares? HistoryObjective-CCocoaEnvironmentDesign

Objective-C TIOBE: Language of the Year Currently ranked #3 Mac and OS X market share continues to rise Flourishing App Store OS X and iOS apps numerous

History 1985: Steve Jobs leaves Apple Jobs founds NeXT Mission: Create powerful computers for universities NeXTSTEP Object-Oriented, Multitasking Operating System Interesting Note Tim Berners-Lee designed and built first web browser on NeXTSTEP 1996: NeXT purchased by Apple NeXTSTEP becomes Mac OS X 2001: Cheetah (10.0) 2012: Mountain Lion (10.8)

Objective-C Object-oriented language ANSI C language (strict superset) Smalltalk-inspired extension Developed in early 80s Stepstone (Brad Cox and Tom Love) Goal: facilitate reusability and backwards compatible to C Features & Constructs Messages Interfaces and Implementation Properties Object Life Cycle ARC Protocols Categories Dynamic Typing

Messages Message is sent Target and interpretation of message calculated runtime Inspired by Smalltalk Bracket Syntax

Interface and Implementation Declaration and Definition Interface Instance variables Properties Method declarations Inheritance Protocol adoption Implementation Definition of methods, properties, protocol conformity

Properties Simple way to declare accessor methods Encapsulation Methods are generated by compiler Allow use of “dot syntax” Declaration contains attributes Writability (readonly, readwrite) Setter semantics (strong, weak, copy, assign, retain) Setter semantics (strong, weak, copy, assign, retain)Atomicity

Object Life Cycle 1210 allocretainrelease Retain-Release Process

Object Life Cycle - ARC ARC: Automatic Reference Counting Automatic memory management Compiler inserts retains and releases Restrictive but effective Bridge casting C-style cast void *

Protocols Declare methods to be implemented by a class Adoption and Conformity Similar to “interface” in Java Objects can be referred to by the adopted protocol id delegate;

Categories Open classes Add methods to existing classes (even those in an imported framework) Extensions Anonymous categories Commonly used to redeclare readonly property as readwrite

Dynamic Typing id type Pointer to Objective-C object Message Forwarding Handle message Drop message Pass it on

Blocks Anonymous Functions Similar to standard C functions Usage Encapsulate code groups to execute concurrently Dispatch Execute on items in a collection Fast enumeration Easily parameterized

Comparison to C++ Objective-C is true superset of C (simple - small addition) C++ is complex - adds features such as templates, operator overloading, etc. C++ is generally faster Objective-C’s runtime is more complex (dynamic typing & message passing) Objective-C is dynamically typed Objective-C has built-in

Cocoa Framework that provides applications the distinctive look and feel often associated with OS X Underlying Frameworks Foundation Kit Application Kit Core Data Other frameworks

Foundation Collection of base layer classes Applications can be created solely with Foundation Command line tools Functionalities General object behavior and life cycle NSObject – base class LocalizationPortabilityWrappersPrimitives Operating system level functionality Ports File I/O Threads

Foundation Classes Contains over 100 different classes NSObject - base class alloc, init, class conformsToProtocol:performSelector:onThread:withObject:waitUntilDone:NSStringNSMutableStringNSArrayNSMutableArrayNSThreadNSDateNSURL

AppKit Contains objects required in creating a graphical application WindowsButtons Scroll Boxes Text Fields Views NSView, NSTextView Controllers NSViewController, NSWindowController

Core Data Provides means to manage the data of an application Data model SerializationXMLBinarySQLitePersistence Managed Objects Command Pattern Undo/Redo

Other Frameworks Audio & Video Core Audio Core Video Core MIDI Graphics/Animation Core Animation Core Image OpenGLQuartzBridges Ruby PythonNetworking Bonjour Kerberos

Environment Great environment  Excellent development experience ToolsXcode General IDE Utilities Apple LLVM Engine Backend Interface Builder Graphical Interface Designer

Xcode General IDE Code Editor LLVM Engine Integration Interface Builder Integration Project Navigation Utilities Version Editor Instruments

Xcode

LLVM Engine Compiler - Clang C/Objective-C/C++ Syntax Highlighting Code Completion Live Issues Fix-it Static Analysis Improper memory allocation Unreachable code Improper loops llvm.org

Interface Builder Integrated into Xcode Design graphical interfaces for application Drag and Drop WYSIWYG IBActions & IBOutlets Connect visual design to code

Interface Builder

Design Objective-C and Cocoa utilize many design patterns and constructs Provides stability and familiarity Design Patterns Model-View-ControllerDelegationOthers…

Model-View-Controller Divides system into three components Model Domain-specific data and operations Platform-independentView Responsible for graphically displaying the model Controller Mediator for the model and view Handles interactions with the system

Model-View-Controller Smalltalk-80 MVC Paradigm ParcPlace Systems, Inc.

Model-View-Controller Controller ModelView Observer Mediator Command

Delegation One class delegates action to another (helper object) Inversion of control Delegate & Delegator Pass notifications No polling Utilizes protocols Delegate conforms to methods for which delegator is aware

Design Patterns Command pattern NSInvocationUndo/redo Observer pattern KVO: Key-Value Observer Adapter pattern Protocols Singleton Pattern NSFileManager NSApplicationMemento Archiving SerializationProxy NSProxy

Design Patterns Composite View Hierarchy DecoratorCategoriesFaçadeNSImage Bitmap (jpg, png) Vector (pdf) Iterator Fast enumeration Mediator Controller classes Abstract Factory Class Clusters NSString NSArray Chain of Responsibility NSResponder AppKit Responder Chain

Demo