How to properly subclass a delegate property in Objective-C?

Question

In subclassing a class, I want to also subclass a delegate of the parent class given that the subclass now has additional functionality. What\'s the best way to go about doing

Answer 1

Follow the example of NSTableView and NSOutlineView.

NSOutlineView is a subclass of NSTableView, and defines its own protocol for its dataSource and delegate.

NSTableView declares its delegate this way:

- (void)setDelegate:(id )delegate;
- (id )delegate;

and NSOutlineView:

- (void)setDelegate:(id )anObject;
- (id )delegate;

Apparently the compiler is more lenient with bare method declarations than it is with property declarations.

Unlike NSTable/OutlineView, you might want to make the subclass's protocol inherit from the base class's protocol, e.g.

 @protocol SpecializedProtocol 

... it probably depends on the situation.