如何运行进度条，直到后台播放音频停止

Question

我正在音频播放器上工作，我必须允许音频在后台播放，我已经完成了音频会话，但是当我在后台播放音频时我停留在进度栏中，然后再次打开我的应用程序进度栏，计时器停止了，我还需要在后台运行它们。我的意思是，如果我移到其他视图或最小化该应用程序，则应该使用计时器更新进度栏。

 @IBAction func btnPlayMusicAction(_ sender: Any)
{
    if isPlaying == false {
        self.btnPlayMusicPro.setImage(#imageLiteral(resourceName: "PauseIcon"), for: .normal)
        self.isPlaying = true
        self.audioPlayer?.play()
        timer = Timer.scheduledTimer(timeInterval:1.0, target: self,selector: (#selector(updateRemainingTime)), userInfo: nil, repeats:true)



    }else{
        self.btnPlayMusicPro.setImage(#imageLiteral(resourceName: "PlayIcon"), for: .normal)
        self.isPlaying = false
        if (audioPlayer?.isPlaying)!{
            self.audioPlayer?.pause()
        }
        self.timer?.invalidate()



    }
}

她是方法updateRemainingTime（）

    @objc func updateRemainingTime(){
    let currentTime =   Int((audioPlayer?.currentTime)!)
    let duration = Int((audioPlayer?.duration)!)
    let seconds = currentTime % 60
    let minutes = (currentTime / 60) % 60
    let hours = (currentTime / 3600)

    var remainingTime:String = ""
    if currentTime >= 3600{
        remainingTime = String(format: "%02d:%02d:%02d", hours, minutes, seconds)
    }else{
        remainingTime = String(format: "%02d:%02d", minutes, seconds)
    }

    self.lblPlayMusicTimePro.text = remainingTime
    Tray.remainingAudioTime = remainingTime

    if currentTime  == duration-1{
        timer?.invalidate()

        if (audioPlayer?.isPlaying)!{
            self.audioPlayer?.currentTime = 0
            self.audioPlayer?.stop()
        }
        self.btnPlayMusicPro.setImage(#imageLiteral(resourceName: "PlayIcon"), for: .normal)
        self.isPlaying = false
        self.musicProgressViewPro.setProgress(0.0, animated: true)
        self.lblPlayMusicTimePro.text = "00:00"
        self.lblMusicTimePro.text = "00:00"
    }else {
        let currentProgress = Float((audioPlayer?.currentTime)! / (audioPlayer?.duration)!)
        Tray.progressTime = currentProgress
        self.musicProgressViewPro.setProgress(currentProgress, animated: true)

    }
}