PROTOCOLS

In Objective C, an object cannot inherit from multiple superclasses, yet it can conform to multiple protocols.  If you need a GameCenterManageDelegate to be inherited by many Views, you can define as shown below.

GameCenterManagerDelegate.h
@protocol GameCenterManagerDelegate <NSObject>

@optional

- (void) processGameCenterAuth: (NSError*) error;

@end

GameCenterManagerDelegate.m

@implementation GameCenterManager

// ... 

@end

GameViewController.h

@interface GameViewController : ViewController <GameCenterManagerDelegate> 

@end