title: Why Admob SDK sample project needs Navigationcontroller to work?
body: <p>I created a new project based on the Admob SDK sample project but stripped out of the rootviewcontroller (UINavigationcontroller). However, it doesn't work. 
  It keeps on complaining it cannot receieve an Ad from network.</p>
  
  <p>When I runs the original project (using UINavigationcontroller) the ads popped up.</p>
  
  <p>That doesn't make sense!!</p>
  
  <p>And check out admobviewprotocol.h. it says the following. Is admob expects the viewcontroller be returned to UINavigationController?? If I don't have that it won't work? How odd!</p>
  
  <p>// Return the current view controller (AdMobView should be part of its view hierarchy).
  // Make sure to return the root view controller (e.g. a UINavigationController, not
  // the UIViewController attached to it) .
  - (UIViewController *)currentViewControllerForAdAdMobView *)adView;</p>