title: Having trouble using custom class as a type within App Delegate
body: <p>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. </p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  
  
  @class ViewController;
  @class iAdClass;
  
  @interface AppDelegate : UIResponder &lt;UIApplicationDelegate&gt;
  @property (strong, nonatomic) UIWindow *window;
  
  @property (strong, nonatomic) ViewController *viewController;
  
  @property (assign) iAdClass*iADObject;
  + (AppDelegate*) sharedApplication;
  + (iAdClass)sharedAd;
  
  @end
  </code></pre>