Some startBrowsingForNearbyPlayersWithReachableHandler questions

Question

I'm trying to get local matchmaking working in GameKit using [[GKMatchmaker sharedMatchmaker] startBrowsingForNearbyPlayersWithReachableHandler:]. Essentially, I'm trying to implement interface-less local matches: as long as there's a player in my local vicinity, I want to connect and start a match. Importantly, I only want to do this for local players: I never want to match automatically over the internet.

I've enabled Game Center for my app in iTunes connect and signed up for a different sandbox account on every device I'm using to test.

I've tried both matchmaking with GKMatchmakerViewController (after authenticating the local player) and programmatic matchmaking with startBrowsingForNearbyPlayersWithReachableHandler:, running the same code on an iPhone 4 and an 4th gen iPod Touch sitting next to each other on my desk. Neither ever finds the other; when using GKMatchmakerViewController the interface for finding nearby players remains at the

Finding Players...

spinner, and when using startBrowsingForNearbyPlayersWithReachableHandler:, the notification block never gets called.

Here's my current block of testing code:

-(void)connectLocal
{
    if( ![GKLocalPlayer localPlayer].isAuthenticated )
    {
        // authenticateLocalPlayer calls connectLocal again after authentication is complete
        [ self authenticateLocalPlayer ];
        return;
    }
    [[GKMatchmaker sharedMatchmaker] startBrowsingForNearbyPlayersWithReachableHandler:^(NSString *playerID, BOOL reachable) {
             NSLog(@"Reachability changed for player %@", playerID );
        } ];
}

The docs are a little sparse & confusing on the subject, especially when it comes to the difference between local mulitplayer and matches over the internet. For instance, it seems to be necessary to authenticate the local player and create a match before finding players to join that match (Creating Any Kind of Match Starts with a Match Request). However this little nugget seems to suggest otherwise:

The standard user interface allows players to discover other nearby players, even when neither player is currently connected to Game Center directly.

Additionally, in the flow described in Searching For Nearby Players, a match request isn't created until step 3, after finding players via the notification block passed to startBrowsingForNearbyPlayersWithReachableHandler:. Unfortunately, I've never got that far.

So, the questions:

1) Am I right in thinking I can call startBrowsingForNearbyPlayersWithReachableHandler: before authenticating the local player? GameKit doesn't throw an error, so I'm assuming it's OK. This may be a rash assumption. Whether I authenticate or not doesn't seem to make much difference.

2) Has anyone successfully implemented local auto-matching using [GKMatchmaker sharedMatchmaker] startBrowsingForNearbyPlayersWithReachableHandler:? Is there good example code anywhere that illustrates the complete flow, from browsing for players to starting a match, all programmatically?

3) There seem to be conflicting reports on the web over whether GameKit-enabled apps can be tested in the iOS Simulator. General consensus seems not, and it's better to test on iOS hardware. I've been using a iPhone 4 & an 4th gen iPod Touch. For those who have successfully tested local multiplayer, what testing setup & methodology did you use?

Answer 1

1) Am I right in thinking I can call startBrowsingForNearbyPlayersWithReachableHandler: before authenticating the local player?

No. startBrowsingForNearbyPlayersWithReachableHandler works by both advertising the existing player and browsing for other players but, most importantly, the information it uses to identify players is the playerID... which won't be available until the player authenticates.

3) There seem to be conflicting reports on the web over whether GameKit-enabled apps can be tested in the iOS Simulator. General consensus seems not, and it's better to test on iOS hardware

GameCenter authentication, achievements, and leaderboards work in the simulator, everything else should be tested on real hardware. I actually recommend the simulator for authentication testing, since it avoids the sandbox/production switch which can make detailed auth testing on devices somewhat confusing. Everything else can only be tested on devices. The simulator doesn't have great support for receiving push notifications which breaks match setup and the general hardware configuration is different enough that match communication isn't unlikely to work right anyway.