title: admob Interstitial auto closing
body: <p>I am using DoubleClick (dfp) ads of admob.
  I want to close/dismiss <strong>Interstitial</strong> after few seconds.
  (Just if user didn't click on the ads).</p>
  
  <p>I can do <code>dismissModalViewControllerAnimated</code> afterDelay, but it's closing the ads even user click on them.</p>
  
  <p>Any suggestions?</p>