Create apps that allow players to interact with each other using GameKit.

GameKit Documentation

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Turn-Based Game and Invitations
I have two devices (iPod, iPhone), each using a different Apple ID. I have an existing game to which I'm adding TBM. When the iPod invites the iPhone, it sends an iMessage invite to the iPhone; when I click on that message, I get "Retrieving", then Game Center in Settings is opened, not my App (same version installed on both devices). I start my App on the iPhone and that match is not shown in the Matchmaker View Controller. When I send an invite from the iPhone to the iPod and I click on the iMessage invite, the app starts but the match isn't listed in the MatchMaker ViewController on the iPod (but is on the iPhone). In addition, when I click on the info circle on the iPhone, it who's the two players and "App Store" under the Game Center name. However, When I do the same on the iPod, it has a "Play your turn" there. Any ideas?
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Nov ’25
Game Center fetchSavedGames sometimes returns empty list of games, although it works correctly on the next tries
I have implemented the Game Center for authentication and saving player's game data. Both authentication and saving player's data works correctly all the time, but there is a problem with fetching and loading the data. The game works like this: At the startup, I start the authentication After the player successfully logs in, I start loading the player's data by calling fetchSavedGames method If a game data exists for the player, I receive a list of SavedGame object containing the player's data The problem is that after I uninstall the game and install it again, sometimes the SavedGame list is empty(step 3). But if I don't uninstall the game and reopen the game, this process works fine. Here's the complete code of Game Center implementation: class GameCenterHandler { public func signIn() { GKLocalPlayer.local.authenticateHandler = { viewController, error in if let viewController = viewController { viewController.present(viewController, animated: false) return } if error != nil { // Player could not be authenticated. // Disable Game Center in the game. return } // Auth successfull self.load(filename: "TestFileName") } } public func save(filename: String, data: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.saveGameData(Data(data.utf8), withName: filename) { savedGame, error in if savedGame != nil { // Data saved successfully } if error != nil { // Error in saving game data! } } } else { // Error in saving game data! User is not authenticated" } } public func load(filename: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.fetchSavedGames { games, error in if let game = games?.first(where: {$0.name == filename}){ game.loadData { data, error in if data != nil { // Data loaded successfully } if error != nil { // Error in loading game data! } } } else { // Error in loading game data! Filename not found } } } else { // Error in loading game data! User is not authenticated } } } I have also added Game Center and iCloud capabilities in xcode. Also in the iCloud section, I selected the iCloud Documents and added a container. I found a simillar question here but it doesn't make things clearer.
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How does Game Kit offline leaderboard submission work?
I do not understand how offline leaderboard submission is supposed to work in Game Kit: While the documentation briefly states that offline submission is supported, how is that even possible when you first have to fetch a leaderboard object in order to then call its submitScore function? How can I get the leaderboard object in the first place when offline? Can anyone enlighten me how this works? Or maybe point me to some relevant documentation?
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GKLeaderboard.loadLeaderboards returns empty array
After authenticating the user I'm loading my Game Center leaderboards like this: let leaderboards = try await GKLeaderboard.loadLeaderboards(IDs: [leaderboardID]) This is working fine, but there are times when this just returns an empty array. When I encounter this situation, the array remains empty for several hours when retrying, but then at some point it suddenly starts working again. Is this a known issue? Or am I hitting some kind of quota maybe (as I do it quite often while developing my game)?. Edit: My leaderboards are grouped in sets if that makes any difference here.
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iOS Matchmaker ViewController Info Button
I'm updating an existing distributed game to add turn-based matches. When the Matchmaker ViewController Info Button next to a game is pressed, the results vary: iOS 15.x - Button under avatar says "Accept Invite" or "View Game" (depending on if invite has already been accepted) iOS 18.x - Button always says "App Store" - I assume that means it would lead one to the App store to install the game. Both devices (iPad 15.x and iPhone 18.x) have the same version of the game installed. The results are the same when running in the simulator. When the game is released, I assume this button will work properly, no?
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2 high scores vanished
In my game 854159268 (com.1791entertainment.qugame), in my quMostRecent3 leaderboard, the top 2 entries have 'vanished'. They were there yesterday. I know these players have played today, as I see their scores on other leaderboards. Any ideas how to get these back? These 2 players (me and my tester) are both TestFlight ing - not sure if that changes things.
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GameKit Turn Based Matches Push Notifications
I'm developing a game that supports GameKit turn based matches. What I don't understand is this: Is tapping on the Game Center notification push messages the only way for the GKTurnBasedEventListener to trigger? What if someone misses the push message (swiping it away by accident or something like that) but still wants to join? Is there some inbox somewhere where the pending messages can be seen or fetched? Also it was mentioned in a very old WWDC video (from 2013, I think that's the latest with information about turn based matches) that the notification also includes a badge for the icon. However, I do not understand how to implement that. Is there any documentation for that?
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How does the automatch feature work in Game Kit?
I'm developing a turn based game. When I present the GKTurnBasedMatchmakerViewController players can opt in for automatch instead of selecting a specific friend as opponent. How exactly does the matching work if a player doesn't specify anything explicitly? Does Game Center send push notifications in a round robin fashion to all friends and the first one to accept is then matched as opponent? Is this documented somewhere?
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