Is there any way to add a generic type parameter to a protocol?

Question

As of Xcode 7, Objective-C introduced generic type parameters for classes. Is there any way to use generics with Objective C protocols? I haven\'t found an obvious way to do thi

Answer 1

If I correctly understand what you're saying you can:

Specify that the object should either be either an instance of or inherit from ObjectType by using:

@protocol MYObjectContainer
- (__kindof ObjectType *)objectAtIndex:(NSUInteger)index;
@end

Specify that the items in a collection (NSArray, NSSet, etc.) should be an instance of ItemType (prefix with '__kindof' to also extend this to objects inheriting from ItemType) by using:

@protocol MYObjectContainer
- (CollectionType <ItemType *> *)objectAtIndex:(NSUInteger)index;
@end

Note that Objective-C generics are designed to prevent hidden bugs by providing compiler warnings when a specified type is not adhered to. They do not actually force the specified type at runtime.