如何在MoviePlayer Swift Xcode

Question

我正在尝试在加载电影之前向moviePlayer添加加载或缓冲，我尝试使用警报但没有工作

查看代码

NSNotificationCenter.defaultCenter().addObserver(self, selector: "moviePlayBackStateChanged:", name: "MPMoviePlayerLoadStateDidChangeNotification",object:  moviePlayer)


    func moviePlayBackStateChanged(notification:NSNotification)
{

    var alert = UIAlertView(title: "Loading", message: "test loading", delegate: self, cancelButtonTitle: "CLose")
    alert.show()

}