title: GameCenter login alert
body: <p>In a game I am developing using GameCenter, I want to handle the following scenario:</p>
  
  <ol>
  <li>the user starts up the game. He is shown the system alert that prompts him to log on GameCenter. He ignores it for now.  </li>
  <li>after a while, the user wants to log in to GameCenter and clicks on(for instance) the Leaderboards menu item. He choses cancel instead of Log in, for now. </li>
  <li>the process repeats several times. Eventually the user DOES want to log in to GameCenter. He clicks the Leaderboard menu item one more time.</li>
  </ol>
  
  <p>In my tests, I have found that the alert popup raised by the call to "authenticateWithCompletionHandler" (as invoked by Apple's sample GameCenterManager) which suggests to log in to GameCenter only appears a limited number of times(4 or 5). The last time it appears, it says "Game Center Disabled, sign in with the Game Center application to enable"Afterwards". Afterwards, calling authenticateWithCompletionHandler no longer does anything visible -no prompt at all. </p>
  
  <p>Playing FruitNinja I tried to replicate this. However, in their case, the popup saying "Game Center Disabled" does appear every time I click on a GameCenter item(Achievements, for instance). </p>
  
  <p>What I'd like to do is to duplicate the functionality: that is, if you are not logged in to GameCenter, to have the standard game center alert appear all the times you click on the Leaderboard menu item. </p>
  
  <p>Is there a way to learn whether the standard 'log in to game center' alert has appeared, or to force it to appear at all times(and not just the first couple of tries)?</p>