title: Detect if interstitial ad is showing
body: <p>Im currently implementing iAd in my first iPhone app. My issue, which i'm having, is to detect if there is actually an interstitial ad showing on my view controller. Because, if there is no ad i would like to show another view.</p>
  
  <p>I have been reading through the iAd programming guide and then found the 'UIViewController iAd Additions Reference' in the docs. This one tells me, my view controller has now a new property called presentingFullScreenAd.</p>
  
  <p>The problem is whenever i call it in viewDidLoad, viewWillAppear or viewDidAppear it returns NO. Except when i close the ad (if there was an ad showing) than it returns YES in viewWillAppear and viewDidAppear but its too late then.</p>
  
  <p>I have set the interstitialPresentationPolicy of the view controller which is showing the ad to ADInterstitialPresentationPolicyAutomatic because i want it to show the ad as often as possible.</p>
  
  <p>Any ideas about this?
  Thanks in advance.</p>