title: Game Center Unavailable Alert View not showing anymore?
body: <p>In my previous SpriteKit games, when the player accesses the game center view controller, he/she is presented with an alert view saying <code>"Game Center Unavailable. Player is not signed in"</code> if he/she is not signed in to Game Center. This alert view shows even if I don't have it in my code. I think it is built-in.</p>
  
  <p>Currently I am working on a new project but am using Swift and Xcode 6.1 this time (as opposed to Objective C and Xcode 6.0). </p>
  
  <p>Now, I noticed that this alert does not show anymore when the player is not signed in when accessing the game center view controller. Did Apple remove it?  Do I have to manually code that now? </p>