title: Problem with ADBannerView in combination with UINavigationController
body: <p>I have the following application:</p>
  
  <p>I have 1 window. On that window I add two views. One view is the view of the UINavigationController. This is used to let the user navigate through my application. The other view has a ADBannerView on it. This view is placed on the bottom of the screen. </p>
  
  <p>The user can navigate through my application without any problems and the ADBannerView keeps on the screen to show advertisements. But when the user clicks on the ADBannerView and close it again the banner is moved to the top of the screen and the UINavigationController views are not responding any more. </p>
  
  <p>Anyone has any idea why this happens and how to resolve this issue?</p>