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OBJECTIVE-C AND IOSFOR .NET DEVELOPERS
EDUARDO SCOZ
CHICAGO ALT.NET
SEPT 2011
ME
• Software Architect at
• .NET Developer for 5-6 years
• iOS Developer for the last 2 years
• Obj-C exclusively for 4 months
• http://escoz.com
• http://twitter.com/escoz
IOS DEV 101
What you need:
• A Mac• Register with Apple Dev Center - $100.00• Download XCode 4 (or beta) • Time and patience
Demo
SO, WHAT IS IT LIKE?
AFTER 6 MONTHS
IOS LIBRARIES ARE GREAT
• CocoaTouch works really well
• Really productive
• Easy to make good stuff fast
• NS objects get a while to get used to
• C functions are necessary every once in a while, which is strange, but not the end of the world
OBJ-C IS UGLY BUT ACCEPTABLE
• You’ll be missing features all the time
• Old language, learn to accept it
• Brackets everywhere
• You’ll go crazy for a few weeks• Once you’re over it, development is just like C#• C code in between is messy
XCODE JUST SUCKS
• Crash Fest
• IDE Helps you very little
• poor code navigation• poor refactoring
• Good to manage project, NIBs and CoreData mappings
• Great performance tool: Instruments
JETBRAINS APPCODE
Beautiful code development
• Doesn’t do everything, but it’s great at what it does
If you’re used to Resharper, you’ll feel at home
Still in beta, so buggy at times
• http://www.jetbrains.com/objc/
OBJ-CCreated in the early 80's, by StepStone
• Adds Smalltalk-like messaging to C
Steve Jobs/NeXT in 88
• added Obj-C compiler support to GCC in 88• uses it to create NeXTStep
Apple acquires NeXT in '96 and builds OSX
BASED ON C LANG
• Any C code is valid Obj-C code
• No namespaces!
• Global functions and variables!
• Obj-C functions are built in C
• Header and implementation files
OBJECT ORIENTED
Just like C#
• Classes, Objects, Constructors• Class methods, instance methods
• No private methods, no class variables
• Brackets, brackets, brackets!
• Alloc/init vs Constructors
• “id” is a pointer to any Obj-C object
Demo
DYNAMIC LANGUAGE
Pointers always used to pass objects around.
Types is used to assist compiler/tools
Message Passing, not method invocation
• Think of every object as a Dictionary of methods• Extremely simple Reflection• Slower than C++, but still really fast
Messages can be executed in a different thread
Messages can be forwarded to other objects
Method swizzling – change implementations at runtime
MORE FEATURES
Categories == Extension methods
Protocols == kind of like interfaces
• @optional and @required
Properties
• every class becomes a dictionary• Convention allows dot notation - KVC
Blocks == lambda expressions
NSPredicates ~= LINQ, but ugly
MORE FEATURES
Key Value Coding
• Allows simple dot notation for properties:
• -(id) valueForUndefinedKey:(NSString *)key {}
KEY VALUE OBSERVING
Every object contains an observer pattern
MEMORY MANAGEMENT
GC, but only in OSX
Manual reference counting
• [obj retain]• [obj release]• [obj autorelease] - autorelease pools
ARC - Automatic Reference Counting
• Solution for GC envy• smart compiler can do exactly what you would do
manually• __block, __weak, __strong
COCOA TOUCH
Based on OSX Cocoa, but not the same
Frameworks to allow apps to run on iOS:
• UIKit, CoreAnimation, OpenAL, MediaLibrary• CoreAudio, Quartz2D, OpenGL, Address Book• Core Location, MapKit, StoreKit, Bonjour, WebKit• BSD Sockets, AV Foundation
UIKIT
Pretty much anything related to the screen:
• Displaying pixels• Handling user input• High level components, like tables, entry fields etc• Orientation, rotation
MVC-based framework to deal with UI
Demo
NIBs - WYSIWYG Editor
Demo
CORE DATA
Apple’s ORM
Managed object graph that can be persisted
• SQLite only for iOS4, Json for new versions
Manages object model versioning
Localization of names and properties
Demo
NOTES
XCode sucks
• Be prepared for a life of frustration• Use AppCode
ObjC is not bad, get used to it
iOS Frameworks are great
• They’re not simple, but they work really well
RESOURCES
http://developer.apple.com
• Apple developer Forums• irc.freenode.com #iPhoneDev
https://github.com/languages/Objective-C/most_watched
• Facebook three20• JSONKit• RestKit - great way of accessing RESTful services• QuickDialog – mine
