loop audio with AVAudioEngine

Question

I always have worked in obj-c, but I want to get my head 'round swift. I am nearly there with my code, but I just don't know how to loop my wav. It stops after one time playing. I have found some instructions, but I haven't found the solution yet for my code. I hope anyone knows the answer and can help me. So the question is: What do I have to do to make my wav loop when pressing @IBAction func playButtonTapped ?? I will give all my code, just to be sure. Thanks in advance:-)

class ViewController: UIViewController {

    @IBOutlet var startAllButton: UIButton!
    var audioEngine = AVAudioEngine()
    var playerNode = AVAudioPlayerNode()



    let timeShift = AVAudioUnitTimePitch()
    let pedoMeter = CMPedometer()
    let bpm: Float = 110


    var avgStarted: Bool = false

    var steps: Int = 0
    var timer = Timer()
    var adjustedBpm: Float = 110

    var timerCount = 10 {
        didSet {
            if timerCount == 0 {
                stopCountingSteps()


            }
        }
    }

    var lastTap: Date? = nil

    @IBOutlet weak var tempoTap: UIButton!
    @IBOutlet weak var slider: UISlider!
    @IBOutlet weak var label: UILabel!
    @IBOutlet weak var playButton: UIButton!
    @IBOutlet weak var timerLabel: UILabel!
    @IBOutlet weak var stepCountLabel: UILabel!
    @IBOutlet weak var avgLabel: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        setup()
    }

    func setup() {
        label.text = "110"
        audioEngine.attach(playerNode)
        audioEngine.attach(timeShift)
        audioEngine.connect(playerNode, to: timeShift, format: nil)
        audioEngine.connect(timeShift, to: audioEngine.mainMixerNode, format: nil)
        audioEngine.prepare()
        timerLabel.text = ""
        stepCountLabel.text = ""
        do {
            try audioEngine.start()
        } catch {
            print("Could not start audio engine")
        }
    }


    @IBAction func sliderValueChanged(_ sender: UISlider) {
        label.text = String(sender.value)



        self.label.text = String(format:"%.f", sender.value)

        adjustedBpm = sender.value
        timeShift.rate = adjustedBpm/bpm

    }

    @IBAction func playButtonTapped(_ sender: Any) {


        let url = Bundle.main.url(forResource: "25loop110", withExtension: ".wav")
              if let url = url {
                  do {
                      let audioFile = try AVAudioFile(forReading: url)


                    timeShift.rate = adjustedBpm/bpm
                      playerNode.scheduleFile(audioFile, at: nil, completionHandler: nil)

                  } catch {
                      print("could not load audio file")
                  }
              } else {
                  print("could not load audio file")
              }
              playerNode.play()

    }

Answer 1

The problem is these lines:

let audioFile = try AVAudioFile(forReading: url)
playerNode.scheduleFile(audioFile, at: nil, completionHandler: nil)

Where’s the loop? Nowhere. That code plays the file once.

You cannot loop with a file in AVAudioEngine. You loop with a buffer. You read the file into a buffer and call scheduleBuffer(buffer, at: nil, options: .loops).