Reset AVAudioEngine - swift

Question

I am creating a basic soundboard app. I have two switches. One that when activated will make the audio slower and lower pitch and one that makes it faster and higher. I have an if else if if statement that looks at those switches and then plays the audio accordingly, however when I try to push it a second time, either for the same sound or a different sound, it crashes.
I'm about 99% sure that this is due to the AVAudioEngine needing to be reset or having the nodes themselves reset, but I am way past being out of my league here. I've searched high and low, but the answer I seem to be finding relate to resetting the player when using different buttons to make the high or low sounds. Any thoughts?
class ViewController: UIViewController {
#IBOutlet weak var sassSwitch: UISwitch!
#IBOutlet weak var chipSwitch: UISwitch!
#IBAction func sassAction(_ sender: UISwitch) {
chipSwitch.setOn(false, animated: true)
}
#IBAction func chipSwitch(_ sender: UISwitch) {
sassSwitch.setOn(false, animated: true)
}
///Playback Engine
private let audioEngine = AVAudioEngine()
///Player's Nodes
private let pitchPlayer = AVAudioPlayerNode()
private let timePitch = AVAudioUnitTimePitch()
///Audio Files to be played
private var audioFile1 = AVAudioFile()
private var audioFile2 = AVAudioFile()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
if let filePath = Bundle.main.path(forResource: "PeteNope", ofType:
"mp3") {
let filePathURL = URL(fileURLWithPath: filePath)
setPlayerFile(filePathURL)
}
if let filePath2 = Bundle.main.path(forResource: "Law_WOW", ofType:
"mp3") {
let filePath2URL = URL(fileURLWithPath: filePath2)
setPlayerFile2(filePath2URL)
}
}
private func setPlayerFile(_ fileURL: URL) {
do {
let file = try AVAudioFile(forReading: fileURL)
self.audioFile1 = file
} catch {
fatalError("Could not create AVAudioFile instance. error: \(error).")
}
}
private func setPlayerFile2(_ fileURL: URL) {
do {
let file = try AVAudioFile(forReading: fileURL)
self.audioFile2 = file
} catch {
fatalError("Could not create AVAudioFile instance. error: \(error).")
}
}
#IBAction func sound1Play(_ sender: UIButton) {
if sassSwitch.isOn {
timePitch.pitch = -300
timePitch.rate = 0.5
audioEngine.attach(pitchPlayer)
audioEngine.attach(timePitch)
audioEngine.connect(pitchPlayer, to: timePitch, format: audioFile1.processingFormat)
audioEngine.connect(timePitch, to: audioEngine.outputNode, format: audioFile1.processingFormat)
pitchPlayer.scheduleFile(audioFile1, at: nil, completionHandler: nil)
// Start the engine.
do {
try audioEngine.start()
} catch {
fatalError("Could not start engine. error: \(error).")
}
pitchPlayer.play()
} else if chipSwitch.isOn {
timePitch.pitch = +500
timePitch.rate = 2.0
audioEngine.attach(pitchPlayer)
audioEngine.attach(timePitch)
audioEngine.connect(pitchPlayer, to: timePitch, format: audioFile1.processingFormat)
audioEngine.connect(timePitch, to: audioEngine.outputNode, format: audioFile1.processingFormat)
pitchPlayer.scheduleFile(audioFile1, at: nil, completionHandler: nil)
// Start the engine.
do {
try audioEngine.start()
} catch {
fatalError("Could not start engine. error: \(error).")
}
pitchPlayer.play()
} else {
timePitch.pitch = +0
timePitch.rate = 1.0
audioEngine.attach(pitchPlayer)
audioEngine.attach(timePitch)
audioEngine.connect(pitchPlayer, to: timePitch, format: audioFile1.processingFormat)
audioEngine.connect(timePitch, to: audioEngine.outputNode, format: audioFile1.processingFormat)
pitchPlayer.scheduleFile(audioFile1, at: nil, completionHandler: nil)
// Start the engine.
do {
try audioEngine.start()
} catch {
fatalError("Could not start engine. error: \(error).")
}
pitchPlayer.play()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

It looks like you might just need to move the attach, connect, and engine.start functions out of the sound1Play function, and put them into viewDidLoad. Currently you're connecting the nodes every action, and restarting the engine multiple times as well.