ios - 为什么beginGeneratingPlaybackNotifications会产生错误？

歌曲更改时，我试图获取通知，但是插入nowPlaying.beginGeneratingPlaybackNotifications时出现错误MPMediaItem does not have a member named beginGeneratingPlaybackNotifications。我该如何解决？

let nowPlaying = MPMusicPlayerController.systemMusicPlayer().nowPlayingItem
let playing = MPNowPlayingInfoCenter.defaultCenter().nowPlayingInfo
let Title = nowPlaying.valueForProperty(MPMediaItemPropertyTitle) as! String
let Artist = nowPlaying.valueForProperty(MPMediaItemPropertyArtist) as! String
let Album = nowPlaying.valueForProperty(MPMediaItemPropertyAlbumTitle) as! String
let duration = nowPlaying.valueForProperty(MPMediaItemPropertyPlaybackDuration) as! NSNumber

class ViewController: UIViewController {

var ID3 = UILabel()

    override func viewDidLoad() {
    super.viewDidLoad()

    var ID3 = UILabel(frame: CGRectMake(0,0,400,400))
    ID3.center = CGPointMake(160, 284)
    ID3.textAlignment = NSTextAlignment.Center
    ID3.text = (("Song: " + Title) + "\n" + ("Artist: " + Artist) + "\n" + ("Album: " + Album))
    ID3.numberOfLines = 3
    self.view.addSubview(ID3)


    //prints into the console what song is currently playing
    println("Song: " + Title)
    println("Artist: " + Artist)
    println("Album: " + Album)

        nowPlaying.beginGeneratingPlaybackNotifications()
        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: "nowPlayingItemIsChanged:",
            name: MPMusicPlayerControllerNowPlayingItemDidChangeNotification,
            object: nil)
         func nowPlayingItemIsChanged(notification: NSNotification){
            println("Player state changed")

        }

最佳答案

beginGeneratingPlaybackNotifications是MPMusicPlayerController上的一种方法。尝试调用MPMusicPlayerController.systemMusicPlayer().beginGeneratingPlaybackNotifications，并确保在完成后与调用MPMusicPlayerController.systemMusicPlayer().endGeneratingPlaybackNotifications保持平衡。