I'm new to Mac/iPhone programming and Objective-C. In C# and Java we have "generics", collection classes whose members can only be of the type declared. For example, in C#
Dictionary<int, MyCustomObject>
can only contain keys that are integers and values that are of type MyCustomObject. Does a similar mechanism exist in Objective-C?
This answer is outdated but remains for historical value. As of Xcode 7, Connor's answer from Jun 8 '15 is more accurate.
No, there are no generics in Objective-C unless you want to use C++ templates in your own custom collection classes (which I strongly discourage).
Objective-C has dynamic typing as a feature, which means that the runtime doesn't care about the type of an object since all objects can receive messages. When you add an object to a built-in collection, they are just treated as if they were type id. But don't worry, just send messages to those objects like normal; it will work fine (unless of course one or more of the objects in the collection don't respond to the message you are sending).
Generics are needed in languages such as Java and C# because they are strong, statically typed languages. Totally different ballgame than Objective-C's dynamic typing feature.
There are no generics in Objective-C.
Arrays are ordered collections of objects. Cocoa provides several array classes, NSArray, NSMutableArray (a subclass of NSArray), and NSPointerArray.
