I'm trying to make a shared iAd bannerview for the view controllers throughout my ios application. I've been attempting to make a singleton class in my app delegate in order to do this but I keep getting an error saying, "interface type 'iAdClass' cannot be returned by value." I have no clue how to fix this, my setup for a singleton may be incorrect also, so any help with that would be appreciated also.
#import <UIKit/UIKit.h>
@class ViewController;
@class iAdClass;
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) ViewController *viewController;
@property (assign) iAdClass*iADObject;
+ (AppDelegate*) sharedApplication;
+ (iAdClass)sharedAd;
@end