Question

I have a protocol that is defined like this:

@protocol Container

- (BOOL)putStuff: (Stuff *) theStuff;

@end

and class with following declaration:

@interface Stuff : NSObject {

}

@property(readwrite,nonatomic,retain) NSObject <Container> * containerHoldingMe;

@end

and I get an error on putStuff declaration — “Expected a type”. If I change the argument of the method to NSObject, however, it compiles OK — so, I think that Objective C just doesn’t allow loop dependence.

In real classes that I’m working at I want to implement two- However, how do I implement such logic without it?

Answer 1

By the time the compiler evaluates your Container protocol, it does not know about your Stuff class. You can let the compiler know about your Stuff class with a forward declaration:

@class Stuff;

@protocol Container

- (BOOL)putStuff: (Stuff *) theStuff;

@end