title: Stop iOS local notifications at particular time
body: <p>My app using User Notification framework to schedule local notifications every 30 minutes. I set a trigger</p>
  
  <pre><code>  var trigger = UNTimeIntervalNotificationTrigger.CreateTrigger(60 * 30, true); 
  </code></pre>
  
  <p>However, i would like to stop these notifications after certain time lets say 9.00 PM. How do i do it?</p>