Think Different: Objective-C for the .NET developer

Think Different: Objective-C for the .NET developer

• 1.
  Objective-C for the .NET(Or Java) developer It’s not as scary as it looks, I promise... @shawnprice84
• 2.
  Common Complaints Too verbose Unmanaged memory Complicatedsyntax Lack of type safety Unfriendly community
• 3.
  Classes and Objects Object-oriented, dynamiclanguage (no type safety) No Namespaces, Prefix class names with 2-3 letters to help differentiate your classes (NSObject)
• 4.
  Interfaces and Implementations An interfaceProvides a contract, but for a single implementation (not reusable)
• 5.
  Properties Autosynthesized vs. Autoimplemented properties Atomicvs nonatomic Strong vs Weak references Accessing a property with dot (“.”) notation uses the synthesized accessor methods
• 6.
  Methods + indicates aclass method (static), indicates an instance method Each parameter should have a description of what the property indicates, the type and the parameter name Call a selector (method) on nil will do nothing (no exception thrown)
• 7.
  Why []? C# Objective-c
• 8.
  Object Initialization alloc -allocates the memory for an object init - initializes the attributes Custom initializers are the equivalent of custom constructors
• 9.
  Delegates Not just methodstubs (like .NET) - full objects with multiple methods Interact with existing classes Respond to events and requests for information
• 10.
  Automatic Reference Counting(ARC) Provides ultra-simplememory management Keeps track of active references to an object When an object’s reference count reaches 0 it’s removed from memory immediately (unlike GC) Only real danger is a circular reference
• 11.
  Avoid a circular reference Delegatesshould always be weak (or unsafe_unretained) and of type “id” If a block is stored in a strongly held property then only pass in weak references to ivars and self
• 12.
  Categories Similar to extensionmethods in C# .NET Adds methods to existing classes without the need to create a new object type
• 13.
  Class Inheritance Works almostexactly like .NET class inheritance Used much less frequently in Objective-C. Categories and Delegates are preferred
• 14.
  Protocols Closest thing tointerfaces in Objective-C Defines a contract that an object must adhere to Can also have optional methods Declare an object adheres to a protocol using <ProtocolName>
• 15.
  Collections NSArray, NSSet, NSDictionary, NSHashTable Collectionsare immutable unless specified (NSMutableArray) Objective-C collections can’t store primitive types (NSNumber, NSString, NSValue) To store primitive types you can use a Cstyle array
• 16.
  Blocks Chunks of codethat can be passed as an argument Similar to anonymous methods
• 17.
  Blocks cont... Declaring ablock reference Invoke the block Be careful to check if block is null
• 18.
  In Conclusion Don’t beafraid to try it Most of the hatred for Objective-c is based on outdated ideas (or poorly written code)
• 19.
  Resources http://developer.apple.com http://www.raywenderlich.com/ @shawnprice84