IOS GameCenter验证登陆

#import "GameKitHelper.h"
#import "GameConstants.h"

@interface GameKitHelper ()
        <GKGameCenterControllerDelegate> {
    BOOL _gameCenterFeaturesEnabled;
}
@end

@implementation GameKitHelper

#pragma mark Singleton stuff

+(id) sharedGameKitHelper {
    static GameKitHelper *sharedGameKitHelper;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedGameKitHelper =
                [[GameKitHelper alloc] init];
    });
    return sharedGameKitHelper;
}

#pragma mark Player Authentication

-(void) authenticateLocalPlayer {

  GKLocalPlayer* localPlayer =
    [GKLocalPlayer localPlayer];

    localPlayer.authenticateHandler =
    ^(UIViewController *viewController,
      NSError *error) {

        [self setLastError:error];

        if ([CCDirector sharedDirector].isPaused)
            [[CCDirector sharedDirector] resume];

        if (localPlayer.authenticated) {
            _gameCenterFeaturesEnabled = YES;
        } else if(viewController) {
            [[CCDirector sharedDirector] pause];
            [self presentViewController:viewController];
        } else {
            _gameCenterFeaturesEnabled = NO;
        }
    };
}
@end

#pragma mark Property setters

-(void) setLastError:(NSError*)error {
    _lastError = [error copy];
    if (_lastError) {
        NSLog(@"GameKitHelper ERROR: %@", [[_lastError userInfo] 
          description]);
    }
}

#pragma mark UIViewController stuff

-(UIViewController*) getRootViewController {
    return [UIApplication 
      sharedApplication].keyWindow.rootViewController;
}

-(void)presentViewController:(UIViewController*)vc {
    UIViewController* rootVC = [self getRootViewController];
    [rootVC presentViewController:vc animated:YES 
      completion:nil];
}