下载音频文件avaudioplayer后未调用方法

Question

这是我的自定义音乐播放器代码。

这是我的单个自定义视图，我将其添加到窗口中，因此每当我进入应用程序时，它都会保留在屏幕上。

我的步骤：

当我第一次调用playCurrentMusic这个方法时，一切正常，播放器正在打开，正在下载音频文件并进行播放。但是，当我第二次调用此方法时，正在下载文件，但没有music(_ url : URL)调用此方法。

//MARK: Music player methods
extension MusicPlayerView : AVAudioPlayerDelegate{

    func playCurrentMusic(_ index : Int){
        player?.stop()
        btnPlay.setImage(UIImage(named : "pause"), for: .normal)

        downloadFileFromURL(url:  URL(string: (totalItems[index].strUrl ?? ""))!)
        print(URL(string: (totalItems[index].strUrl ?? ""))!)
        currentItemId = index
    }

    func music(_ url : URL){

        do {

            if totalItems.count > 0{
                DispatchQueue.main.async {

                    self.loader.stopAnimating()

                    self.loader.isHidden = true
                    self.btnPlay.isHidden = false

                    MPNowPlayingInfoCenter.default().nowPlayingInfo = [MPMediaItemPropertyTitle: self.totalItems[self.currentItemId].title ?? ""]

                    self.lblTitle.text = self.totalItems[self.currentItemId].title
                    self.lblDesc.text = self.totalItems[self.currentItemId].desc

                    self.commandCenter.playCommand.addTarget(handler: { (event) -> MPRemoteCommandHandlerStatus in
                        self.btnPlay_Click(self.btnPlay)
                        return .success
                    })

                    self.commandCenter.pauseCommand.addTarget(handler: { (event) -> MPRemoteCommandHandlerStatus in
                        self.btnPlay_Click(self.btnPlay)
                        return .success
                    })

                }
            }

            player = try AVAudioPlayer(contentsOf: url)

            isPlaying = true
            if player?.isPlaying == true {
                player?.pause()
            }

            if totalItems.count > 0{
                let asset = AVURLAsset(url: URL(string: (totalItems[currentItemId].strUrl ?? ""))!)
                DispatchQueue.main.async {
                    self.musicSlider.maximumValue = Float(Double(CMTimeGetSeconds(asset.duration)))
                    self.startTimer()
                }
            }else{
               let asset = AVURLAsset(url: url)
                DispatchQueue.main.async {
                    self.musicSlider.maximumValue = Float(Double(CMTimeGetSeconds(asset.duration)))
                    self.startTimer()
                }
            }

            player?.delegate = self
            player?.prepareToPlay()
            player?.play()

        } catch let error as NSError {
            print(error)
        }

    }

    // Delegate method for AVAudioPlayerDelegate which is called every time when song finished.
    func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool){

        if totalItems.count > 0{
            if flag {
                if ((currentItemId + 1) == totalItems.count) {
                    currentItemId = 0
                }else{
                    currentItemId += 1
                }
            }
            downloadFileFromURL(url:  URL(string: (totalItems[currentItemId].strUrl ?? ""))!)
        }else{
            isPlaying = false
            btnPlay.setImage(UIImage(named : "playDark"), for: .normal)
        }
    }

    func downloadFileFromURL(url:URL){

        var downloadTask:URLSessionDownloadTask
        loader.isHidden = false
        btnPlay.isHidden = true
        loader.startAnimating()
        downloadTask = URLSession.shared.downloadTask(with: url, completionHandler: { [weak self](URL, response, error) -> Void in

            self?.music(URL!)
        })

        downloadTask.resume()

    }
}

将音乐播放器添加到appdelegate中的代码

func loadMusicPlayer(_ currentItemIndex : Int, items : [PlayerModel]) {

        self.window?.rootViewController?.view.endEditing(true)

        let player = MusicPlayerView()

        player.frame = CGRect(x: 0, y: AppConstants.ScreenSize.SCREEN_HEIGHT - 156, width: AppConstants.ScreenSize.SCREEN_WIDTH, height: 156)
        player.currentItemId = currentItemIndex
        player.totalItems = items
        player.tag = 1111

        var isFound = false
        for vw in UIApplication.shared.keyWindow!.subviews{
            if vw is MusicPlayerView{
                isFound = true
            }
        }

        if !isFound{
            UIApplication.shared.keyWindow?.addSubview(player)
        }

        player.playCurrentMusic(currentItemIndex)

    }