Swiftui Firebase现在可播放音频AVPlayerItem。无法转换类型为'；StorageReference'；到预期的参数类型'；URL'；

我似乎不知道如何通过firebase将我的流式音频制作成一个现在可以在Xcode 12中使用SwiftUI播放的应用程序。 这是我的密码。我向苹果寻求帮助，他们给了我一个样本，使用应用程序内部保存的m4a音频。我正在使用Firebase实时播放音频、封面艺术、接收歌曲标题和艺术家信息。我只是想弄清楚如何使它现在可以用最少的代码播放。该代码适用于应用程序中存储的url和音频，但通过Firebase流式传输则不起作用。所有的信息、音频和艺术都上传到Firebase并实时显示，因此我可以立即上传新音乐，而无需在应用商店中更新应用程序。我只知道如何用SwiftUI编写代码

        import AVFoundation
        import MediaPlayer
        import Firebase

// Static metadata about each song.

struct Album: Identifiable, Codable, Equatable, Hashable {

    var id = UUID()
    var name : String
    var image: String
    var artist: String
    var songs : [Song]

    enum CodingKeys: String, CodingKey {
        case name
        case image
        case artist
        case songs
    }
}

struct Song: Identifiable, Codable, Equatable, Hashable {

var id = UUID()
var name : String
var image: String
var artist: String
var time: String
var file: String

    enum CodingKeys: String, CodingKey {
        case name
        case image
        case artist
        case time
        case file
    }
}

struct datatype: Identifiable, Equatable, Hashable {

    var id : String
    var image : String
}

struct DynamicMetadata {
    var playerState: PlayerState
    var playerRate: Float
    var totalTime: Float
    var elapsedTime: Float
}

// Possible values of the `playerState` property.
enum PlayerState {
    case stopped
    case playing
    case paused
}

class AudioPlayer: ObservableObject {
    
    // MARK: Playback Machinery
    
    // The songs being played.
    
    private var songItems: [Song]
    
    // The player used to play individual songs.
    private var player: AVPlayer!
    
    // Index of the currently playing item.
    private var currentItemIndex = 0
    
    // The currently playing item.
    @Published private(set) var currentStaticMetadata: Song?
    
    // The current logical state of the player.
    private(set) var playerState: PlayerState = .stopped
    
    // The current playback state.
    @Published private(set) var currentDynamicMetadata: DynamicMetadata?
    
    // `true` if the current session has been interrupted by another app.
    private var isInterrupted: Bool = false
    
    // Observers of notifications and property changes.
    private var itemObserver: NSKeyValueObservation!
    private var rateObserver: NSKeyValueObservation!
    private var statusObserver: NSObjectProtocol!
    private var interruptionObserver: NSObjectProtocol!
    private var timeObserver: Any!
    
    init(metadata: [Song]) {
        songItems = metadata
    }
    
    // MARK: State Changes
    
    // Update Now Playing Info when the current item changes.
    private func handlePlayerItemChange() {
        guard playerState != .stopped else { return }
        
        // Set the Now Playing Info from static item metadata.
        let songItem = songItems[currentItemIndex]
        let nowPlayingInfoCenter = MPNowPlayingInfoCenter.default()
        var nowPlayingInfo = [String: Any]()
        
        nowPlayingInfo[MPNowPlayingInfoPropertyMediaType] = MPNowPlayingInfoMediaType.audio.rawValue
        nowPlayingInfo[MPMediaItemPropertyTitle] = songItem.name
        nowPlayingInfo[MPMediaItemPropertyArtist] = songItem.artist
        nowPlayingInfo[MPMediaItemPropertyAlbumTitle] = songItem.name
        
        nowPlayingInfoCenter.nowPlayingInfo = nowPlayingInfo
        
        // And set it for the UI too.
        currentStaticMetadata = songItem
    }
    
    // Update Now Playing Info when playback rate or position changes.
    private func handlePlaybackChange() {
        guard playerState != .stopped else { return }
        
        // Find the current item.
        
        guard let currentItem = player.currentItem else { stop(); return }
        guard currentItem.status == .readyToPlay else { return }
        
        // Set the Now Playing Info from dynamic metadata.
        let playbackInfo = DynamicMetadata(playerState: playerState, playerRate: player.rate, totalTime: Float(currentItem.duration.seconds), elapsedTime: Float(currentItem.currentTime().seconds))
        let nowPlayingInfoCenter = MPNowPlayingInfoCenter.default()
        var nowPlayingInfo = nowPlayingInfoCenter.nowPlayingInfo ?? [String: Any]()
        
        nowPlayingInfo[MPMediaItemPropertyPlaybackDuration] = playbackInfo.totalTime
        nowPlayingInfo[MPNowPlayingInfoPropertyElapsedPlaybackTime] = playbackInfo.elapsedTime
        nowPlayingInfo[MPNowPlayingInfoPropertyPlaybackRate] = playbackInfo.playerRate
        nowPlayingInfo[MPNowPlayingInfoPropertyDefaultPlaybackRate] = 1.0
        
        nowPlayingInfoCenter.nowPlayingInfo = nowPlayingInfo
        
        // And set it in the UI too.
        currentDynamicMetadata = playbackInfo
    }
    
    // Handle an audio session interruption notification.
    private func handleAudioSessionInterruption(notification: Notification) {
        
        // Retrieve the interruption type from the notification.
        
        guard let userInfo = notification.userInfo,
            let interruptionTypeUInt = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
            let interruptionType = AVAudioSession.InterruptionType(rawValue: interruptionTypeUInt) else { return }
        
        // Begin or end an interruption.
        switch interruptionType {
            
        case .began:
            isInterrupted = true

        case .ended:
            
            // When an interruption ends, determine whether playback should resume
            // automatically, and reactivate the audio session if necessary.
            
            do {
                try AVAudioSession.sharedInstance().setActive(true)
                
                isInterrupted = false
                var shouldResume = false
                if let optionsUInt = userInfo[AVAudioSessionInterruptionOptionKey] as? UInt,
                    AVAudioSession.InterruptionOptions(rawValue: optionsUInt).contains(.shouldResume) {
                    shouldResume = true
                }
                
                switch playerState {
                case .stopped:
                    break
                    
                case .playing where shouldResume:
                    player.play()
                    
                case .playing:
                    playerState = .paused
                    
                case .paused:
                    break
                }
            }
            
            // When the audio session cannot be resumed after an interruption,
            // invoke the handler with error information.
                
            catch {
                print(error.localizedDescription)
            }
            
        @unknown default:
            break
        }
    }
    
    // MARK: Utilities
        
    private func playerItem(atIndex itemIndex: Int) -> AVPlayerItem {
            let songItem = songItems[itemIndex]
            let songURL = Storage.storage().reference(forURL: songItem.file)
            songURL.downloadURL { (url, error) in
                if error != nil {
                    print("error")
                } else {
    
                    do {
                        try AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playback, mode: .default)
    //                    try AVAudioSession.sharedInstance().setActive(true)
                    }
                    catch {
                    // report for an error
                    }
    //                var player = AVPlayer(url: url!)
                    self.player = AVPlayer(url: url!) //
    //                data.player = try! AVAudioPlayer(contentsOf: URL(fileURLWithPath: url!))
    //                data.player = try! AVAudioPlayer(contentsOf: url!)
                    self.player.play()
    //                self.isPlaying = true
    //                self.showcontrols = true
    //                audioPlayer.playPauseTrack()
                }
            }
            return AVPlayerItem(url: songURL)
        }

---

我猜错误来自这里：

return AVPlayerItem(url: songURL)

您已将

songURL

声明为

let songURL=Storage.Storage（）.reference（forURL:songItem.file）

，这意味着它是

StorageReference

，而

AVPlayerItem

无法处理

---

问题是，您无法在那里返回有效的内容，因为下载URL尚未加载。我不确定AVPlayerItem是做什么的，但您可能想看看是否可以稍后构建它-在回调中，您已经在那里做了

self.player=AVPlayer（url:url！）

您已经共享了很多代码，而我并没有阅读所有代码来查看错误发生的确切位置（提示：您可能想了解一下）。但是从错误消息来看，您似乎需要从文件中删除，或者为了播放它。谢谢。我把代码缩短了一点。我真的很感谢你的帮助。希望这有助于理解我的问题。嘿@Vic。你在这方面有什么进展吗？我试着在下面给出一个答案。你有没有机会阅读并尝试一下？如果我的答案有用，请单击向上投票按钮(▲) 如果它回答了您的问题，请单击复选标记(✓) 接受它。这样别人就会知道你已经（足够）了帮助。也请看@Frank我感谢你的回答，但这并没有帮助我成功编译。当我问他们时，苹果公司非常含糊。我没有看到任何Firebase代码将文件下载到内存或磁盘。此外，你的问题标题中的错误是准确的；对存储空间的引用与URL不同。此外这里的代码太多了，我们无法解析；230行大约是200行。请将其缩小到您用于下载文件的代码范围，并确保允许读取所述数据。