I'm building a game with a client-server architecture. Using GKMatch.chooseBestHostingPlayer(_:) rarely works. When I started testing it today, it worked once at the very beginning, and since then it always succeeds on one client and returns nil on the other client. I'm testing with a Mac and an iPhone. Sometimes it fails on the Mac, sometimes on the iPhone. On the device that it succeeds on, the provided host can be the device itself or the other one. I created FB9583628 in August 2021, but after the Feedback Assistant team replied that they are not able to reproduce it, the feedback never went forward. import SceneKit import GameKit #if os(macOS) typealias ViewController = NSViewController #else typealias ViewController = UIViewController #endif class GameViewController: ViewController, GKMatchmakerViewControllerDelegate, GKMatchDelegate { var match: GKMatch? var matchStarted = false override func viewDidLoad() { super.viewDidLoad() GKLocalPlayer.local.authenticateHandler = authenticate } private func authenticate(_ viewController: ViewController?, _ error: Error?) { #if os(macOS) if let viewController = viewController { presentAsSheet(viewController) } else if let error = error { print(error) } else { print("authenticated as \(GKLocalPlayer.local.gamePlayerID)") let viewController = GKMatchmakerViewController(matchRequest: defaultMatchRequest())! viewController.matchmakerDelegate = self GKDialogController.shared().present(viewController) } #else if let viewController = viewController { present(viewController, animated: true) } else if let error = error { print(error) } else { print("authenticated as \(GKLocalPlayer.local.gamePlayerID)") let viewController = GKMatchmakerViewController(matchRequest: defaultMatchRequest())! viewController.matchmakerDelegate = self present(viewController, animated: true) } #endif } private func defaultMatchRequest() -> GKMatchRequest { let request = GKMatchRequest() request.minPlayers = 2 request.maxPlayers = 2 request.defaultNumberOfPlayers = 2 request.inviteMessage = "Ciao!" return request } func matchmakerViewControllerWasCancelled(_ viewController: GKMatchmakerViewController) { print("cancelled") } func matchmakerViewController(_ viewController: GKMatchmakerViewController, didFailWithError error: Error) { print(error) } func matchmakerViewController(_ viewController: GKMatchmakerViewController, didFind match: GKMatch) { self.match = match match.delegate = self startMatch() } func match(_ match: GKMatch, player: GKPlayer, didChange state: GKPlayerConnectionState) { print("\(player.gamePlayerID) changed state to \(String(describing: state))") startMatch() } func startMatch() { let match = match! if matchStarted || match.expectedPlayerCount > 0 { return } print("starting match with local player \(GKLocalPlayer.local.gamePlayerID) and remote players \(match.players.map({ $0.gamePlayerID }))") match.chooseBestHostingPlayer { host in print("host is \(String(describing: host?.gamePlayerID))") } } }

In my SceneKit game I'm able to connect two players with GKMatchmakerViewController. Now I want to support the scenario where one of them disconnects and wants to reconnect. I tried to do this with this code: nonisolated public func match(_ match: GKMatch, player: GKPlayer, didChange state: GKPlayerConnectionState) { Task { @MainActor in switch state { case .connected: break case .disconnected, .unknown: let matchRequest = GKMatchRequest() matchRequest.recipients = [player] do { try await GKMatchmaker.shared().addPlayers(to: match, matchRequest: matchRequest) } catch { } @unknown default: break } } } nonisolated public func player(_ player: GKPlayer, didAccept invite: GKInvite) { guard let viewController = GKMatchmakerViewController(invite: invite) else { return } viewController.matchmakerDelegate = self present(viewController) } But after presenting the view controller with GKMatchmakerViewController(invite:), nothing else happens. I would expect matchmakerViewController(_:didFind:) to be called, or how would I get an instance of GKMatch? Here is the code I use to reproduce the issue, and below the reproduction steps. Code Run the attached project on an iPad and a Mac simultaneously. On both devices, tap the ship to connect to GameCenter. Create an automatched match by tapping the rightmost icon on both devices. When the two devices are matched, on iPad close the dialog and tap on the ship to disconnect from GameCenter. Wait some time until the Mac detects the disconnect and automatically sends an invitation to join again. When the notification arrives on the iPad, tap it, then tap the ship to connect to GameCenter again. The iPad receives the call player(_:didAccept:), but nothing else, so there’s no way to get a GKMatch instance again.

We are trying to implement saving and fetching data to and from iCloud, but it have some problems. MacOS: 15.3 Here is what I do: Enable Game Center and iCloud capbility in Signing & Capabilities, pick iCloud Documents, create and select a Container. Sample code: void SaveDataToCloud( const void* buffer, unsigned int datasize, const char* name ) { if(!GKLocalPlayer.localPlayer.authenticated) return; NSData* data = [ NSData dataWithBytes:databuffer length:datasize]; NSString* filename = [ NSString stringWithUTF8String:name ]; [[GKLocalPlayer localPlayer] saveGameData:data withName:filename completionHandler:^(GKSavedGame * _Nullable savedGame, NSError * _Nullable){ if (error != nil) { NSLog( @"SaveDataToCloud error:%@", [ error localizedDescription ] ); } }]; } void FetchCloudSavedGameData() { if ( !GKLocalPlayer.localPlayer.authenticated ) return; [ [ GKLocalPlayer localPlayer ] fetchSavedGamesWithCompletionHandler:^(NSArray<GKSavedGame *> * _Nullable savedGames, NSError * _Nullable error) { if ( error == nil ) { for ( GKSavedGame *item in savedGames ) { [ item loadDataWithCompletionHandler:^(NSData * _Nullable data, NSError * _Nullable error) { if ( error == nil ) { //handle data } else { NSLog( @"FetchCloudSavedGameData failed to load iCloud file: %@, error:%@", item.name, [ error localizedDescription ] ); } } ]; } } else { NSLog( @"FetchCloudSavedGameData error:%@", [ error localizedDescription ] ); } } ]; } Both saveGameData and fetchSavedGamesWithCompletionHandler are not reporting any error, when debugging, saveGameData completionHandler got a nil error, and can get a valid "savedGame", but when try to rebot the game and use "fetchSavedGamesWithCompletionHandler" to fetch data, we got nothing, no error reported, and the savedGames got a 0 length. From this page https://developer.apple.com/forums/thread/718541?answerId=825596022#825596022 we try to wait 30sec after authenticated , then try fetchSavedGamesWithCompletionHandler, still got the same error. Checked: Game Center and iCloud are enabled and login with the same account. iCloud have enough space to save. So what's wrong with it.