CloudKit不会播放CKAsset Song Swift 3

Question

我将一首歌存储在CloudKit中作为CKAsset。我成功检索了这首歌并没有得到任何错误，但它不会播放。任何帮助将不胜感激，谢谢。

我的AVPlayer在课堂上懒惰地实例化。

//Create song player to play song, lazily instantiated
lazy var songPlayer: AVPlayer = {
    let player = AVPlayer()
    return player
}()

func playPause() {

    //Unwrap song - if there is no song, then return...you can't play something that is not there.
    guard let song = selectedArtist.song else {
        return
    }

    //Create player item
    let playerItem = AVPlayerItem(url: song.fileURL)

    //Add observer so app knows when the song reached its end
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(itemDidFinishPlaying(notification:)),
        name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
        object: playerItem)

    //Assign playerItem to AVPlayer
    songPlayer = AVPlayer(playerItem: playerItem)

    if isSongPlaying {
        print("Song at \(song.fileURL) stopped.")
        isSongPlaying = false;
        songPlayer.pause()
        songPlayPauseImageView.image = UIImage(named: "play.png")
    } else {
        print("Song at \(song.fileURL) started.")
        isSongPlaying = true;
        songPlayer.play()
        songPlayPauseImageView.image = UIImage(named: "pause.png")
    }
}

当我开始播放歌曲时，我收到了消息（正如预期的那样）：

Song at file：/// private / var / mobile / Containers / Data / Application / E34BE227-86DD-4AD7-A3C1-6A0610CE8C39 / Library / Caches / CloudKit / 6e22c352bc4bdeb0b75d42a0d681d67c69eeaad4 / Assets / 6BD84822-D039-4228-A5E9- 59CB281BB964.0182fa97976e7d7b941bb8d8790ea75c6d3b72c302已开始。

不幸的是，这首歌没有播放。