如何使用 AVQueuePlayer 播放歌曲？

Question

我似乎找不到AVQueuePlayer的可理解文档或示例。 我目前正在尝试更改我的AudioManager ，以便我可以播放包含多首或单首歌曲的专辑。 我将不胜感激有关AVQueuePlayer的任何代码示例或好文章。

这是我播放一首歌曲的代码库：

final class AudioManager: ObservableObject {
    var player: AVAudioPlayer?
    @Published var isPlaying: Bool = false
    
    func startPlayer(track: String) {
        guard let url = Bundle.main.url(forResource: track, withExtension: "mp3") else {return}
        
        do {
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
            try AVAudioSession.sharedInstance().setActive(true)
            player = try AVAudioPlayer(contentsOf: url)
            player?.play()
            isPlaying = true
        } catch {
            print("Failed to initialize player: ", error)
        }
    }
    
    func playPause() {
        guard let player = player else {
            print("Instance of audio player not found")
            return
        }
        if player.isPlaying {
            player.pause()
            isPlaying = false
        } else {
            player.play()
            isPlaying = true
        }
    }
    
    func stop() {
        guard let player = player else {
            return
        }
        if player.isPlaying {
            player.stop()
            isPlaying = false
        }
    }
    
}

到目前为止，这是我尝试使用新AudioQueueManager class 所做的事情：

import Foundation
import AVKit

final class AudioQueueManager: ObservableObject {
    var player: AVQueuePlayer?
    @Published var isPlaying: Bool = false
    @Published var someType: SomeType = .album(Album.data)
    
    func startPlayer(someType: SomeType) {
        switch someType {
        case .song(let song):
            let url = Bundle.main.url(forResource: song.track, withExtension: "mp3")
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)
                player = AVQueuePlayer(url: url!)
                player?.play()
                isPlaying = true
            } catch {
                print("Failed to initialize player: ", error)
            }
        case .album(let album):
            var items: [AVPlayerItem] = []
            album.songs?.forEach({ albumsong in
                items.append(AVPlayerItem(url: Bundle.main.url(forResource: albumsong.track, withExtension: "mp3")!))
            })
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)
                player = AVQueuePlayer(items: items)
                player?.play()
                isPlaying = true
            } catch {
                print("Failed to initialize player: ", error)
            }
        }
    }
    
    func playPause() {
        guard let player = player else {
            print("Instance of audio player not found")
            return
        }
        if player.timeControlStatus == .playing {
            player.pause()
            isPlaying = false
        } else {
            player.play()
            isPlaying = true
        }
    }
    
    func stop() {
        guard let player = player else {
            return
        }
            player.removeAllItems()
            isPlaying = false
        
    }
    
}

停止/开始新歌曲/专辑不起作用，我找不到AVQueuePlayer的player.stop()等效项。 也尝试转发 10 秒不能像以前一样工作： audioManager.player?.currentTime += 10我尝试这样做audioQueueManager.player?.currentTime().value += 10但值不可变，访问 currentTime 也是不再可能，因为它需要 CMTime 而不是 Int。

这就是我在视图中启动播放器的方式：

enum SomeType {
    case song(Song)
    case album(Album)
}
@EnvironmentObject var audioQueueManger: AudioQueueManager
switch type {
                case .song(let song):
//                    audioManager.stop()
//                    audioManager.isPlaying = true
//                    audioManager.startPlayer(track: song.track)
                    audioQueueManager.stop()
                    audioQueueManager.isPlaying = true
                    audioQueueManager.startPlayer(someType: .song(song))
                    
                    musicPlayerVm.addCurrentSong()
                case .album(let album):
//                    audioManager.stop()
//                    audioManager.isPlaying = true
//                    audioManager.startPlayer(track: album.songs?[0].track ?? "track1")
                    audioQueueManager.stop()
                    audioQueueManager.isPlaying = true
                    audioQueueManager.startPlayer(someType: .album(album))
                }

这对于一首歌曲来说效果很好。 如果我在一首歌之后开始一首歌曲或专辑，则设置player = nil有效，但如果我在专辑当前正在播放时尝试播放专辑，则会收到错误消息： "An AVPlayerItem cannot be associated with more than one instance of AVPlayer"

Answer 1

我没有找到任何有用的资源来了解AVQueuePlayer但AVAudioPlayer无论如何都可以做我想做的事情。 我的代码中的某些部分仍然需要调整，但这是我想出的：

import Foundation
import AVKit

final class AudioQueueManager: ObservableObject {
    var player: AVAudioPlayer?
    @Published var isPlaying: Bool = false
    @Published var someType: SomeType = .album(Album.data)
    @Published var currentAlbumsong: AlbumSong = AlbumSong.data
    var currentTrack = 0
    var urls: [URL] = []
    var currentAlbum: Album = Album.data

    func startPlayer(someType: SomeType) {
        switch someType {
        case .song(let song):
            self.someType = .song(song)
            let url = Bundle.main.url(forResource: song.track, withExtension: "mp3")
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)
                player = try AVAudioPlayer(contentsOf: url!)
                player?.play()
                isPlaying = true
            } catch {
                print("Failed to initialize player: ", error)
            }
        case .album(let album):
            self.someType = .album(album)
            album.songs?.forEach({ albumsong in
                if urls.count < album.songs!.count {
                    urls.append(Bundle.main.url(forResource: albumsong.track, withExtension: "mp3")!)
                }
            })
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)
                player = try AVAudioPlayer(contentsOf: urls[currentTrack])
                currentAlbum = album
                currentAlbumsong = album.songs![currentTrack]
                player?.play()
                isPlaying = true
            } catch {
                print("Failed to initialize player: ", error)
            }
        }
    }
    
    func previousTrack() {
        if currentTrack - 1 < 0 {
            currentTrack = (urls.count - 1) < 0 ? 0 : (urls.count - 1)
        } else {
            currentTrack -= 1
        }
        playTrack()
    }

    func nextTrack() {
        if currentTrack + 1 > urls.count - 1 {
               currentTrack = 0
           } else {
               currentTrack += 1;
           }
           playTrack()
    }

    func playTrack() {
        if urls.count > 0 {
            player?.pause()
            player = nil
            player = try? AVAudioPlayer(contentsOf: urls[currentTrack])
            currentAlbumsong = currentAlbum.songs![currentTrack]
            player?.play()
            isPlaying = true
        }
    }
    
    func playPause() {
        guard let player = player else {
            print("Instance of audio player not found")
            return
        }
        if player.isPlaying {
            player.pause()
            isPlaying = false
        } else {
            player.play()
            isPlaying = true
        }
    }
    
    func stop() {
        currentTrack = 0
        player = nil
        urls.removeAll()
        isPlaying = false
    }
}

实现看起来仍然和上面一样。