You can do it like this also
@protocol GEMEditItemViewControllerDelegate;
@interface GEMEditItemViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
@property GEMItem *item;
@property (weak) id<GEMEditItemViewControllerDelegate> delegate;
@end
@protocol GEMEditItemViewControllerDelegate <NSObject>
@required
- (void)controller:(GEMEditItemViewController *)controller didUpdateItem:(GEMItem *)item;
@end