Swift - Game Center not available

Question

I\'m trying to implement Game Center in my Swift game. I have a menu view controller, where the user can press a \"SCORES\" button, which should take them to the Game Center

Answer 1

Assuming that you've enabled Game Center in your app and also added a leaderboard in iTunes Connect then you need to authenticate your player before you can show GC. Also, be sure that you've created a test user in iTunes Connect that you can use to log in to Game Center when the prompt appears.

Your MenuViewController should authenticate the local player in viewDidLoad like so:

class MenuViewController: UIViewController,
            GKGameCenterControllerDelegate
{
    var leaderboardIdentifier: String? = nil
    var gameCenterEnabled: Bool = false

    override func viewDidLoad()
    {
        super.viewDidLoad()

        //Your code that sets up your scene or other set up code

        //HERE IS WHERE YOU AUTHENTICATE
        authenticateLocalPlayer()
    }

    func authenticateLocalPlayer()
    {
        var localPlayer = getLocalPlayer() // see GKLocalPlayerHack.h
        localPlayer.authenticateHandler =
            { (viewController : UIViewController!, error : NSError!) -> Void in
                if viewController != nil
                {
                    self.presentViewController(viewController, animated:true, completion: nil)
                }
                else
                {
                    if localPlayer.authenticated
                    {
                        self.gameCenterEnabled = true
                        localPlayer.loadDefaultLeaderboardIdentifierWithCompletionHandler
                        { (leaderboardIdentifier, error) -> Void in
                            if error != nil
                            {
                                print("error")
                            }
                            else
                            {
                                self.leaderboardIdentifier = leaderboardIdentifier
                                print("\(self.leaderboardIdentifier)") //in your example "VHS" should be returned
                            }
                        }
                    }
                    else
                    {
                        print("not able to authenticate fail")
                        self.gameCenterEnabled = false

                        if error
                        {
                            print("\(error.description)")
                        }
                        else
                        {
                            print(    "error is nil")
                        }
                    }
                }
        }
    }


    func gameCenterViewControllerDidFinish(gameCenterViewController: GKGameCenterViewController!)
    {
        gameCenterViewController.dismissViewControllerAnimated(true, completion: nil)
    }    
}

After you've successfully authenticated then you should be able to present Game Center.

Note the line: var localPlayer = getLocalPlayer() // see GKLocalPlayerHack.h

To get that to work you need to do a little hack to get GKLocalPlayer to instantiate correctly in Swift.

Create a new class in Objective-C and name the file GKLocalPlayerHack.h/m

In the header put:

//  GKLocalPlayerHack.h
// Issue with GameKit and Swift
// https://stackoverflow.com/questions/24045244/game-center-not-authenticating-using-swift

#import 

@interface GKLocalPlayerHack : NSObject

GKLocalPlayer *getLocalPlayer(void);

@end

In the implementation file put:

// GKLocalPlayerHack.m
// Issue with GameKit and Swift
// https://stackoverflow.com/questions/24045244/game-center-not-authenticating-using-swift

#import "GKLocalPlayerHack.h"

@implementation GKLocalPlayerHack

GKLocalPlayer *getLocalPlayer(void)
{
    return [GKLocalPlayer localPlayer];
}

@end

Be sure to add:

#import "GKLocalPlayerHack.h"

To your bridging header. Credit to @marmph for his answer in this question: Game Center not authenticating using Swift