Objective c protocol generics

Question

Can Objective-C protocol be generic?

Following this tutorial, I'm basically looking for something like that:

@protocol ItemsStore<__covariant ObjectType> <NSObject>

-(NSArray <ObjectType> *)items;

@end

Which is a generic protocol for some ObjectType that "implements" ("inherits") another protocol NSObject

Answer 1

As @rmaddy suggested, and as referred to this questions, it is NOT possible. Shame, moving to Swift then...

Answer 2

Maybe you could just redefine it as generic in the interface.

@protocol ItemsStore <NSObject>

- (NSArray *)items;

@end

@interface MyItemsStore<ObjectType> : NSObject <ItemsStore>

- (NSArray <ObjectType> *)items;

@end

This seems an unlikely scenario though. You might be better just defining the type of the items in each subclass. Like what Apple do with NSFetchRequest in their core data model generation.