UISlider to control AVAudioPlayer

Question

I\'m trying to implement a little function in my app. I am currently playing sounds as AVAudioPlayers and that works fine. What I would like to add is to control the sound\'

Answer 1

Problems that I've faced during playing an audio file and show start/end time and controlling the song with the UISlider.

1. Not playing audio directly without downloading it in temp folder.
2. UISlider got crashed on main thread in lower iOS version i.e 12.4/13.1
3. Smooth Scrolling of UISlider.
4. Calculating and updating the start/end time of the song.

This answer needs some editing, but it will work without any doubt.

  //UISlider init
  lazy var slider: UISlider = {
    let progress = UISlider()
    progress.minimumValue = 0.0
    progress.maximumValue = 100.0
    progress.tintColor = UIColor.init(named: "ApplicationColor")
    return progress

}()

 var audioPlayer : AVAudioPlayer?
   //First I've downloaded the audio and then playing it.
  override func viewWillAppear(_ animated: Bool) {

    super.viewWillAppear(animated)


    timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(trackAudio), userInfo: nil, repeats: true)

    if let audioURLString = audioURL{
        let urlstring = URL(string: audioURLString)!
        downloadFromURL(url: urlstring) { (localURL, response, error) in
            if let localURL = localURL{
                self.playAudioFile(url: localURL)
            }

        }
    }
}

 override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)
    stopTimer()
}


// Stop TimeInterval After View disappear
func stopTimer() {
    if timer != nil {
        timer?.invalidate()
        audioPlayer?.stop()
        audioPlayer = nil
        timer = nil
    }
}
@objc func sliderSelected(_ sender : UISlider){

    if audioPlayer != nil{
        if !isPlaying{
            self.audioPlayer?.play()
            playButton.setImage(UIImage.init(named: "AudioPause"), for: .normal)
            isPlaying = true
        }else{
            self.audioPlayer?.currentTime = TimeInterval(Float(sender.value) * Float(self.audioPlayer!.duration) / 100.0)
            if (sender.value / 100.0 == 1.0){

                //Do something if audio ends while dragging the UISlider.

            }
        }


    }

}
 func downloadFromURL(url:URL,completion: @escaping((_ downladedURL: URL?,_ response :URLResponse?,_ error: Error?) -> Void)){
    var downloadTask:URLSessionDownloadTask
    downloadTask = URLSession.shared.downloadTask(with: url) {(URL, response, error) in
        if let url = URL{
            completion(url,nil,nil)
        }else if let response = response{
            completion(nil,response,nil)
        }
        if let error = error{
            completion(nil,nil,error)
        }


    }

    downloadTask.resume()
}


func playAudioFile(url:URL){
    do{

        self.audioPlayer = try AVAudioPlayer(contentsOf: url)
        self.audioPlayer?.prepareToPlay()
        self.audioPlayer?.delegate = self
        self.audioPlayer?.play()

   let audioDuration = audioPlayer?.duration
        let audioDurationSeconds = audioDuration
        minutes = Int(audioDurationSeconds!/60);
        seconds =  Int(audioDurationSeconds!.truncatingRemainder(dividingBy: 60))
    } catch{
        print("AVAudioPlayer init failed")
    }
}

@objc func trackAudio() {

    if audioPlayer != nil{
        DispatchQueue.main.async {
            print("HI")
            let normalizedTime = Float(self.audioPlayer!.currentTime * 100.0 / self.audioPlayer!.duration)
            self.slider.setValue(normalizedTime, animated: true)
            let currentTime = self.audioPlayer?.currentTime
            self.currentMinutes = Int(currentTime!/60);
            self.currentSeconds =  Int(currentTime!.truncatingRemainder(dividingBy: 60))
            self.startTimeLabel.text =  String(format: "%02i:%02i", self.currentMinutes, self.currentSeconds)
            self.endTimeLabel.text = String(format: "%02i:%02i", self.minutes, self.seconds)
        }
    }





}