title: iOS Game Center. How to pass data while inviting a friend?
body: <p>The game i'm developing has three different modes of action. But when a player invites another player to the game through GameKit, the recipient device is not aware what mode exactly it should play. Is it possible somehow to pass any type of data along with invitation?</p>
  
  <p><strong>What i have already tried</strong> The only idea which came to my mind was to set <code>defaultInvitationMessage</code> property of <code>MatchMakerViewController</code> on inviting device to a specific value, like "Let's play first mode", but unfortunately i have no idea how to retrieve it on recipient device when it receives the message. And moreover, this property may be edited by user when sending the invitation. After thorough studying of GameKit documentation for three hours i couldn't find anything which could bring me closer to the solution. </p>
  
  <p>So, again - Is there any possibility to notify the remote device which type of the game it must play after the invitation has been accepted?
  Thanks, everyone</p>