What does id<…> mean in Objective-C?

Question

I\'m trying to use Google Analytics in an iOS application, and I saw this portion of code :

id tracker = [[GAI sharedInstance] defaultTrack         


        

Answer 1

The <> means that the object conforms to the protocol (pr protocols) inside the square brackets.

On your example, the object tracker can be any type of object but it conforms to the GAITracker protocol.

Therefore, although it doesn't have a specific class you can still call methods and properties on it that are declared by that protocol.