iOS 8 and later

Starting in iOS 8, all devices can simply invite any peer they detect while browsing. Multipeer Connectivity will automatically process both invites so that both peers join the same MCSession.

iOS 7

In iOS 7, sending simultaneous invites can cause both invites to fail, leaving both peers unable to communicate with each other. Apps can work around this by programmatically selecting one of the peers to send the invite. Many approaches are possible for selecting the inviting peer, but the simplest is to compare the hash values of the two MCPeerID and select the highest as shown in Listing 1

Listing 1  Choosing which MCPeerID will invite

- (void)browser: (MCNearbyServiceBrowser*) browser

                 foundPeer: (MCPeerID*) nearbyPeerID

                 withDiscoveryInfo: (NSDictionary *) info

{

   // Compare the hash values of the 2 peers IDs

   if ((uint32_t)myPeerID.hash > (uint32_t)nearbyPeerID.hash)

   {

      [self.browser invitePeer:nearbyPeerID

                           toSession:session

                           withContext:nil

                           timeout:15];

   }

   else

   {

      // NSLog(@"Skipping invite on: %@", [myPeerID description]);

   }

}