ios - 如何在 iOS10 (Swift 3) 中获取正在播放歌曲的歌词

Question

我想显示 iOS 系统播放器当前正在播放的歌曲的歌词。

这是我的自定义播放器:

import UIKit
import MediaPlayer
import AVFoundation

class NowPlayingController: NSObject {
    var musicPlayer: MPMusicPlayerController {
        if musicPlayer_Lazy == nil {
            musicPlayer_Lazy = MPMusicPlayerController.systemMusicPlayer()

            let center = NotificationCenter.default
            center.addObserver(self,
                selector: #selector(self.playingItemDidChange),
                name: NSNotification.Name.MPMusicPlayerControllerNowPlayingItemDidChange,
                object: musicPlayer_Lazy)
            musicPlayer_Lazy!.beginGeneratingPlaybackNotifications()
        }

        return musicPlayer_Lazy!
    }
    private var musicPlayer_Lazy: MPMusicPlayerController?

    var nowPlaying: MPMediaItem?

    //If song changes
    func playingItemDidChange(notification: NSNotification) {
        nowPlaying = musicPlayer.nowPlayingItem
    }
}

为了从 nowPlaying 项目获取歌词，我尝试了两种方法，它们都总是返回nil。

此代码始终返回 nil:

let lyricsText = nowPlaying?.value(forProperty: MPMediaItemPropertyLyrics) as? NSString as String?

在下面的代码中 MPMediaItemPropertyAssetURL 总是返回 nil 而不是实际的 URL:

let songUrl = nowPlaying?.value(forProperty: MPMediaItemPropertyAssetURL) as? NSURL as URL?
if songUrl != nil {
    let songAsset = AVURLAsset(url: songUrl!, options: nil)
    lyricsText = songAsset.lyrics

All songs are on device (synced by iTunes), contain lyrics (displayed in system player) and non DRM-protected (ripped aac/mp3).

我正在真实设备上对此进行测试:iPhone 6s/iOS 10.3

关于如何获取歌词或为什么 MPMediaItemPropertyAssetURL 返回 nil 的任何建议？

Answer 1

我不知道为什么它不起作用，但看起来相同的代码现在可以正常工作了。也许它以某种方式连接到我现在用于播放器实例的单例。这是 100% 工作的 Swift 3 版本:

import UIKit
import MediaPlayer
import AVFoundation

class NowPlayingController: NSObject {

    static let sharedController = NowPlayingController()

    //MARK: Init
    private override init () {
        super.init()

        var musicPlayer_Lazy: MPMusicPlayerController?

        // System player instance
        if musicPlayer_Lazy == nil {
            musicPlayer_Lazy = MPMusicPlayerController.systemMusicPlayer()
            NotificationCenter.default.addObserver(self,
                                               selector: #selector(self.playingItemDidChange),
                                               name: NSNotification.Name.MPMusicPlayerControllerNowPlayingItemDidChange,
                                               object: musicPlayer_Lazy)
            musicPlayer_Lazy!.beginGeneratingPlaybackNotifications()
        }

        self.musicPlayer = musicPlayer_Lazy!
    }

    // MARK: Class properties
    var musicPlayer: MPMusicPlayerController!
    var nowPlaying: MPMediaItem?

    // MARK: Methods
    func playingItemDidChange(notification: NSNotification) {
        nowPlaying = musicPlayer.nowPlayingItem
        NotificationCenter.default.post(newSongNotification as Notification)
    }

    func getLyrics() {
        let songUrl = nowPlaying?.value(forProperty: MPMediaItemPropertyAssetURL) as? URL
        let songAsset = AVURLAsset(url: songUrl!, options: nil)
        let lyricsText = songAsset.lyrics
    }
}