What is the best way to convert NSNumber into NSString?

Consider below declaration of Song object and tell proper way to call name property?

Considering the following Objective-C code, what will get printed:

The Objective-C code ... @interface MyClass : NSObject ... @end

Which one is NOT correct about Protocols ?

In which situation you would NOT use void types?

Objective-C methods with certain names (“init”, “alloc”, etc.) always return objects that are an instance of the receiving class’s type; such methods are said to have a “related result type”. A method with a related result type can be declared by using:

How can you temporarily disable layer actions in a Core Animation?

What is (void*)0 ?

What are the two types of predicates?

What is a persistent object store?