迅速。显示透明背景的视频

Question

我的主视图有一些不同的类别，当玩家完成100％的类别时，我想要五彩纸屑下雨。

我将五彩纸屑视为视频（只有五彩纸屑可见，背景是透明的）我试图用MPMoviePlayer在我的视图上显示视频，如下所示：

let path = NSBundle.mainBundle().pathForResource("Confetti", ofType:"mov")
let url = NSURL.fileURLWithPath(path!)
self.moviePlayer = MPMoviePlayerController(contentURL: url)

if let player = self.moviePlayer {
    player.view.frame = CGRect(x: 0, y: 0, width: self.view.bounds.height * 1.2 * (1920/1080), height: self.view.bounds.height * 1.2)
    player.view.frame.origin.x = 0 - (player.view.frame.width - self.view.bounds.width) / 2
    player.backgroundView.backgroundColor = UIColor.clearColor()
    player.view.backgroundColor = UIColor.clearColor()

    for subView in self.moviePlayer!.view.subviews as [UIView] {
        subView.backgroundColor = UIColor.clearColor()
    }

    player.prepareToPlay()
    player.scalingMode = .AspectFill
    player.controlStyle = .None
    self.view.addSubview(player.view)
}

但它不起作用，这就是显示：

如何使其发挥作用，或者还有其他方法可以做到这一点？