Obj-C and iOS for .NET Developers

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

iOSDev 101
What you need:
A Mac
Register with Apple Dev Center - $100.00
Download XCode4 (or beta)
Time and patience
Demo

So, what is it like?
After 6 months

iOS libraries are great
CocoaTouchworks 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

Jetbrainsappcode
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-C
Created 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/initvs 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]
[objautorelease] - 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 RESTfulservices
QuickDialog – mine

THANKS!
Eduardo Scoz
escoz@redpointtech.com
http://escoz.com
http://twitter.com/escoz

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Obj-C and iOS for .NET Developers

by escoz on Sep 15, 2011

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