Can't connect players in GameKit using GKMatchmaker.shared().findMatch

Question

Created Jan ’22

Replies 0

Boosts 0

Participants 1

I'm trying to connect two players with each other using GameKit in a very simple game. I want to use GKMatchmaker.shared().findMatch as I don't want to show any GameCenter related view controllers. (to keep it simple)

Problem:

Even though GameKit creates a match after finding two players, an error occurs that prevents either player from sending any message to the others.

Current Situation:

The basic code is as follows (based on the docs described here: https://developer.apple.com/documentation/gamekit/finding_multiple_players_for_a_game)

print("Requesting multiplayer match")
let request = GKMatchRequest()
request.minPlayers = 2
request.maxPlayers = 2
request.recipientResponseHandler = {(player: GKPlayer, respnse: GKInviteRecipientResponse) -> Void in
    print("new player about to join")
    print(player.alias)
    print(respnse)
}

GKMatchmaker.shared().findMatch(for: request, withCompletionHandler: {
    (match: GKMatch?, error: Error?) -> Void in
    if error != nil {
        // Handle the error that occurred finding a match.
        print("error during matchmaking")
        print(error as Any)
    } else if match != nil {
        guard let match = match else { return }

        print("connected to \(match.players.count) players")

        // load the multiplayer data handler
        let handler = MultiMatchHandler()
        match.delegate = handler

        // load the multiplayer service
        let service = MultiMatchService(match: match)
        service.sendMessageToAll(text: "Hello from the other side")

        // finish the match making
        GKMatchmaker.shared().finishMatchmaking(for: match)

        // Start the game with the players in the match.
        self.view?.presentScene(GameScene.newScene(multiplayer: service))
    }

})

The output of that is

Requesting multiplayer match
2022-01-05 01:19:16.554959+0100 Grapefruit[38300:10026027] [Match] cannot set connecting state for players: (
    "<GKPlayer: 0x282add280>(alias:... gamePlayerID:... teamPlayerID:... name:... status:(null) friendBiDirectional:0 friendPlayedWith:1 friendPlayedNearby:0 acceptedGameInviteFromThisFriend:0 initiatedGameInviteToThisFriend:0 automatchedTogether:1)"
), as there is no inviteDelegate set yet. The state might directly change to Ready when we set the inviteDelegate later and call sendQueuedStatesAndPackets.
2022-01-05 01:19:16.557002+0100 Grapefruit[38300:10026027] [Match] syncPlayers failed to loadPlayersForLegacyIdentifiers: (
    "..."
)
connected to 0 players
sending text Hello from the other side failed

Findings:

minPlayers is set to 2. As the completion handler is called this means that at least one more player was found. But the number of players returned in match.players.count is 0
The matcher shows an error saying that cannot set connecting state for players ... as there is no inviteDelegate set yet. I can't find any info about this invite delegate.

Actual Question:

What is an inviteDelegate? Do I really need to implement such (if yes, then how?)? (I don't think so as the docs state that the match only starts after the invites are accepted). How can I resolve this issue?

Boost