title: calling a method after each 60 seconds in iPhone
body: <p>I have created an GKSession and as its object is created, it starts search for availability of devices, as</p>
  
  <pre><code> - (void)session:(GKSession *)session peer:(NSString *)peerID didChangeState:(GKPeerConnectionState)state {
  </code></pre>
  
  <p>I want to call this method after each 60 seconds, what should I do?</p>