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

Given this example that produces the warning:

// Class A
@protocol ClassADelegete;

@interface ClassA : NSObject
@property (nonatomic, weak) id delegate;
@end

@protocol ClassADelegete 
- (void)classADidSomethingInteresting:(ClassA *)classA;
@end

// Class B
@protocol ClassBDelegete;

@interface ClassB : ClassA
@property (nonatomic, weak) id delegate; // Warning here
@end

@protocol ClassBDelegete 
- (void)classBDidSomethingElse:(ClassB *)classB;
@end

Two solutions that remove the warning are.

1) In the subclass, place the protocol definition before the class definition. This is what UITableViewDelegate in UITableView.h does:

// Class B
@class ClassB;

@protocol ClassBDelegete 
- (void)classBDidSomethingElse:(ClassB *)classB;
@end

@interface ClassB : ClassA
@property (nonatomic, weak) id delegate;
@end

2) In the subclass, add the original protocol alongside the new one:

// Class B
@protocol ClassBDelegete;

@interface ClassB : ClassA
@property (nonatomic, weak) id delegate;
@end

@protocol ClassBDelegete 
- (void)classBDidSomethingElse:(ClassB *)classB;
@end

I assume (1) works as Apple do it this way, Option (2) removes the warning but I haven't compiled and run anything setup this way.