title: How to send silent push to iOS via Google Cloud Messaging
body: <p>How to send silent push notification to iOS application over GCM?</p>
  
  <p>Silent push is notification that will not appear in notification center, but awake application to do some action in background.
  Google introduce new features in new <a href="https://developers.google.com/cloud-messaging/">GCM</a> with possibility to send push messages to Android, Chrome and iOS.</p>
  
  <p>Any idea, how to do this?</p>