loop audio with AVAudioEngine - ios

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).