title: When is didRegisterForRemoteNotificationsWithDeviceToken called?
body: <p>There are a lot of questions about didRegisterForRemoteNotificationsWithDeviceToken but they all sidestep a very direct question which I cannot seem to find an exact answer to.</p>
  
  <p>For an app which is properly set up for notifications in all other ways and has proper network connectivity: when is didRegisterForRemoteNotificationsWithDeviceToken called?  Some possible choices might be:</p>
  
  <ol>
  <li>Every time the app starts</li>
  <li>Only after the initial prompt to the user to accept push notifications</li>
  <li>Something else?</li>
  </ol>