Having an ivar 'delegate' in a subclass whose superclass also has same named ivar

Question

I have a subclass defined like this

@protocol UMTextViewDelegate;

@interface UMTexView : UITextView <UITextViewDelegate> {

}

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

@end

@protocol UMTextViewDelegate <NSObject>
@optional
- (void)textViewDidSelectWordToDefine:(UMTexView*)textView;
@end

But I get a warning Property type 'id<UMTextViewDelegate>' is incompatible with type 'id<UITextViewDelegate>' inherited from 'UITextView'.

How do I suppress this warning ? I tried adding this :

@protocol UMTextViewDelegate <NSObject, UITextViewDelegate>

but no luck. !!

EDIT:

I am not using ARC

Answer 1

The problem you are having is about forward declarations. In the place where you are declaring the delegate, the compiler doesn't know that UMTextViewDelegate descends from UITextViewDelegate. The only thing it knows is that UMTextViewDelegate is a protocol.

You have to create a forward declaration for the class @class UMTexView;, then put the protocol declaration and then the class declaration.

On a separate note, it's obvious UMTexView is supposed to be the text delegate for itself. Maybe it would be easier to have UMTexView descending directly from UIView and put an UITextView inside it. Then you wouldn't have any problem with delegate collisions and the UITextViewDelegate would be unaccessible externally.

Answer 2

Using @Sulthan's answer, this is what I came up with and it squished the warning.

@class UMTextView;

@protocol UMTextViewDelegate <NSObject, UITextViewDelegate>
@optional
- (void)textViewDidSelectWordToDefine:(UMTextView*)textView;
@end

@interface UMTextView : UITextView <UITextViewDelegate>

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

@end

The forward declaration of UMTextView followed by protocol declaration tells UMTextView that UMTextViewDelegate is indeed descends from UITextViewDelegate. That way I don't have to the route of adding a uiview and then adding a uitextview inside that view.