Game Center Multiplayer using GKMatch but seems can't be connected - iphone

Question

Hi I'm a new bie in Game Center for iOS. I'm trying to add the multiplayer feature using matches to my game and following the documentation.
So far I reached a point where 2 of my clients can successfully get a match, i.e. the matchmakerViewController:didFindMatch callback is called and a GKMatch object is delivered.
However after that I seems to be stuck there forever, because according to the documentation, I'll have to wait until all the players (2 in my case) are actually connected before starting my game. But it seems the match:player:didChangeState callback is never called to indicate a successful connection. Well, I'm sure my clients are all in the same wifi network ( or is it a must?) Could any one enlighten me on this case? Do I have to do any extra things to make the clients to connect? Thanks a lot for the help!

Answer 1

So I was running into this and the solution (for me) was somewhat embarrasing. I had copied and pasted a bunch of the code from the Apple docs..and they left out an obvious step. They never actually set the match's delegate!
My code now is:
- (void)matchmakerViewController:(GKMatchmakerViewController *)viewController didFindMatch:(GKMatch *)match {
[self dismissModalViewControllerAnimated:YES];
self.myMatch = match; // Use a retaining property to retain the match.
self.myMatch.delegate = self; // THIS LINE WAS MISSING IN THE APPLE DOCS. DOH.
// Start the game using the match.
NSLog(#"Match started! Expected Player Count:%d %#",match.expectedPlayerCount, match.playerIDs);}
Once I actually set the match delegate, the functions get called. Doh.

Answer 2

When you get the GKMatch object, be sure to check the expectedPlayerCount property. It is possible that the other player is already connected, and thus you will not get a match:player:didChangeState on the delegate.

Answer 3

I have had the same problem with a friend. The solution was quite strange but it works afterwards. On all devices you have to enable the Notifications (Sounds/Alerts/Badges) for the Game Center inside the Settings/Notifications options. Afterwards we could establish a connection and did receive a match object

Answer 4

Inside your callback matchmakerViewController:didFindMatch
Add this code then you'll see the callback "match:player:didChangeState" being called by GC
GKMatchRequest *request = [[[GKMatchRequest alloc] init] autorelease];
request.minPlayers = 2;
request.maxPlayers = 2;
[[GKMatchmaker sharedMatchmaker] addPlayersToMatch:match matchRequest:request completionHandler:^(NSError* error) {
if(error)
NSLog(#"Error adding player: %#", [error localizedDescription]);
}];

Answer 5

It was working all along. The only difference is that... when you use invites the event "didChangeState" doensn't get called. You're connected without notice and you can start to receive data. I never tried to send/receive data... cuz i was expecting the event first, but i did send something by mistake one time, and it worked. :)
- (void)matchmakerViewController:(GKMatchmakerViewController *)viewController didFindMatch:(GKMatch *) match {
//Dismiss window
[self dismissModalViewControllerAnimated:YES];
//Retain match
self.myMatch = match;
//Delegate
myMatch.delegate = self;
//Flag
matchStarted = TRUE;
//Other stuff
}
- (void)match:(GKMatch *)match player:(NSString *)playerID didChangeState:(GKPlayerConnectionState)state {
//This code gets called only on auto-match
}
The above code works as expected.

Answer 6

Make sure that you've set your class as the delegate for GKSession. The class will need to implement the GKSessionDelegate protocol... otherwise, it'll never receive this callback. Here's the protocol reference. Hope this helps!