- (void)viewDidLoad
{
    [self.activityIndicator startAnimating];
    [self authenticatePlayer];

    self.skView.backgroundColor = [SKColor blueColor];

    // During this time the grey screen is visible as the assets are being loaded and take ~1 second
    // self.skView.scene is NULL here so I cannot set the backgroundColor...

    [GamePlayScene loadSceneAssetsWithCompletionHandler:^{
        [self.activityIndicator stopAnimating];
        self.activityIndicator.hidden = YES;

        CGSize viewSize = self.skView.bounds.size;

        self.gamePlayScene = [[GamePlayScene alloc] initWithSize:viewSize];
        self.adView.autoresizingMask = UIViewAutoresizingFlexibleWidth;

        [self.skView presentScene:self.gamePlayScene];

    }];
    ...

self.scene.backgroundColor = [SKColor blueColor];

- (void)viewDidLoad
{
[super viewDidLoad];

// Configure the view.
SKView * skView = (SKView *)self.view;
skView.showsFPS = YES;
skView.showsNodeCount = YES;
/* Sprite Kit applies additional optimizations to improve rendering performance */
skView.ignoresSiblingOrder = YES;

// Create and configure the scene.
GameScene *scene = [GameScene sceneWithSize:skView.bounds.size];
scene.scaleMode = SKSceneScaleModeAspectFill;
scene.backgroundColor = [UIColor blackColor];

// Present the scene.
[skView presentScene:scene];
}