Why is there no * in front of delegate declaration ?

Question

Hey guys,

I just noticed there is no * in front of the declaration for a delegate ...

I did something like this :

@protocol NavBarHiddenDelegate;


@interface AsyncImageView : UIView {

    NSURLConnection* connection;
    NSMutableData* data;
    UIActivityIndicatorView *indicator;

    id <NavBarHiddenDelegate> delegate;

}

@property (nonatomic, assign) id <NavBarHiddenDelegate> delegate;

- (id)initWithUrl:(NSString*)url;

@end


@protocol NavBarHiddenDelegate 

- (void)hideNavBar;

@end

It works perfectly well but as I am used to always but a * in front of objects I declare, why not for this one ?!?

Thank you,

Gotye.

Answer 1

Because id already has its implicit *. If you ignore the protocol restriction then

id <NavBarHiddenDelegate> delegate;

becomes

id delegate;

which obviously doesn't need a *. BTW, if the protocol is put on an ObjC type then you need the *, e.g.

XXViewController<NavBarHiddenDelegate>* delegate;

Answer 2

This has nothing to do with delegates.

The type id is different, for historical reasons; think of it as any-object *. Whenever you write id, there is no *.

If there were a single root class Object for all Objective-C objects then you could imagine that typedef Object * id; — but there isn't, so id is different (well, actually, it's defined as something like struct objc_object * if I recall correctly, but you shouldn't worry about that implementation-detail-with-respect-to-this-level).