Game Center authentication for both iOS 5 and iOS 6

gistfile1.m

- (void) authenticateLocalPlayer
{
    GKLocalPlayer *localPlayer = [GKLocalPlayer localPlayer];
    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"6.0")) {
        // iOS 6
        localPlayer.authenticateHandler = ^(UIViewController *viewController, NSError *error){
            if (viewController != nil)
            {
                [navController_ presentViewController:viewController animated:false completion:nil];
            }
            else if (localPlayer.isAuthenticated)
            {
             //   [self authenticatedPlayer: localPlayer];
            }
            else
            {
               // [self disableGameCenter];
            }
        };
    } else {
        // iOS 5
        [localPlayer authenticateWithCompletionHandler:^(NSError *error) {
            if (localPlayer.isAuthenticated)
            {
                // Perform additional tasks for the authenticated player.
            }
            else {
            }
        }];
    }
}