ViewController.swift

func checkIfFirstLaunch(){
	if UserDefaults.standard.bool(forKey: "HasLaunchedBefore"){
		print("App has launched before")
	} else {
		print("This is the first launch ever!")
		UserDefaults.standard.set(true, forKey: "HasLaunchedBefore")
		UserDefaults.standard.set(0.0, forKey: "Slider Value Key")
		UserDefaults.standard.synchronize()
	}

	func application(_ application: UIApplication, willFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool{
		print("App Delegate: will finish launching")
	}

}

override func viewDidLoad(){
	super.viewDidLoad()

	do {
		audioPlayer = try AVAudioPlayer(contentsof: receivedAudio.filePathUrl as URL)
	} catch _ {
		audioPlayer = nil
	}
	audioPalyer.enableRate = true

	audioEngine = AVAudioEngine()
	do {
		audioFile = try AVAudioFile(forReading: receivedAudio.filePathUrl as URL)
	} catch _ {
		audioFile = nil
	}

	sliderView.value = UserDefaults.standard.float(forKey: SliderValueKey)

	setUserInterfaceToPlayMode(false)
}

	@IBAction func playAudio(_ sender: UIButton){
		let pitch = sliderView.value

		playAudioWithVariablePitch(pitch)
		setUserInterfaceToPlayMode(true)

		UserDefaults.standard.set(sliderView.value, forKey: SliderValueKey)
	}