extension may not contain stored properties and no member problems in swift - swift

Question

I am not able to understand why I am getting these errors. someone please help me. Here is the source code
import UIKit
import AVFoundation
// MARK: - PlaySoundsViewController: AVAudioPlayerDelegate
extension PlaySoundsViewController: AVAudioPlayerDelegate {
var audioEngine = AVAudioEngine()
// MARK: Alerts
struct Alerts {
static let DismissAlert = "Dismiss"
static let RecordingDisabledTitle = "Recording disabled"
static let RecordginDisabledMessage = "Youve disabled this app from recording your microphone. Check settings"
static let RecodingFailedTitle = "Recording failed"
static let RecordingFailedMessage = "Something went wrong with the recording"
static let AudioRecordedError = "Audio Recorder Error"
static let AudioSessionError = "Audio Session Error"
static let AudioRecordingError = "Audio Recording Error"
static let AudioFileError = "Audio File Error"
static let AudioEngineError = "Audio Engine Error"
}
// MARK: PlayingState (raw values correspond to sender tags)
enum PlayingState { case playing, notPlaying }
// MARK: Audio Functions
func setupAudio() {
// initialize (recording) audio file
do {
audioFile = try AVAudioFile(forReading: recordedAudioURL as URL)
} catch {
showAlert(Alerts.AudioFileError, message: String(describing: error))
}
}
func playSound(rate: Float? = nil, pitch: Float? = nil, echo: Bool = false, reverb: Bool = false) {
// initialize audio engine components
audioEngine = AVAudioEngine()
// node for playing audio
audioPlayerNode = AVAudioPlayerNode()
audioEngine.attach(audioPlayerNode)
// node for adjusting rate/pitch
let changeRatePitchNode = AVAudioUnitTimePitch()
if let pitch = pitch {
changeRatePitchNode.pitch = pitch
}
if let rate = rate {
changeRatePitchNode.rate = rate
}
audioEngine.attach(changeRatePitchNode)
// node for echo
let echoNode = AVAudioUnitDistortion()
echoNode.loadFactoryPreset(.multiEcho1)
audioEngine.attach(echoNode)
// node for reverb
let reverbNode = AVAudioUnitReverb()
reverbNode.loadFactoryPreset(.cathedral)
reverbNode.wetDryMix = 50
audioEngine.attach(reverbNode)
// connect nodes
if echo == true && reverb == true {
connectAudioNodes(audioPlayerNode, changeRatePitchNode, echoNode, reverbNode, audioEngine.outputNode)
} else if echo == true {
connectAudioNodes(audioPlayerNode, changeRatePitchNode, echoNode, audioEngine.outputNode)
} else if reverb == true {
connectAudioNodes(audioPlayerNode, changeRatePitchNode, reverbNode, audioEngine.outputNode)
} else {
connectAudioNodes(audioPlayerNode, changeRatePitchNode, audioEngine.outputNode)
}
// schedule to play and start the engine!
audioPlayerNode.stop()
audioPlayerNode.scheduleFile(audioFile, at: nil) {
var delayInSeconds: Double = 0
if let lastRenderTime = self.audioPlayerNode.lastRenderTime, let playerTime = self.audioPlayerNode.playerTime(forNodeTime: lastRenderTime) {
if let rate = rate {
delayInSeconds = Double(self.audioFile.length - playerTime.sampleTime) / Double(self.audioFile.processingFormat.sampleRate) / Double(rate)
} else {
delayInSeconds = Double(self.audioFile.length - playerTime.sampleTime) / Double(self.audioFile.processingFormat.sampleRate)
}
}
// schedule a stop timer for when audio finishes playing
self.stopTimer = Timer(timeInterval: delayInSeconds, target: self, selector: #selector(PlaySoundsViewController.stopAudio), userInfo: nil, repeats: false)
RunLoop.main.add(self.stopTimer!, forMode: RunLoopMode.defaultRunLoopMode)
}
do {
try audioEngine.start()
} catch {
showAlert(Alerts.AudioEngineError, message: String(describing: error))
return
}
// play the recording!
audioPlayerNode.play()
}
func stopAudio() {
if let audioPlayerNode = audioPlayerNode {
audioPlayerNode.stop()
}
if let stopTimer = stopTimer {
stopTimer.invalidate()
}
configureUI(.notPlaying)
if let audioEngine = audioEngine {
audioEngine.stop()
audioEngine.reset()
}
}
// MARK: Connect List of Audio Nodes
func connectAudioNodes(_ nodes: AVAudioNode...) {
for x in 0..<nodes.count-1 {
audioEngine.connect(nodes[x], to: nodes[x+1], format: audioFile.processingFormat)
}
}
// MARK: UI Functions
func configureUI(_ playState: PlayingState) {
switch(playState) {
case .playing:
setPlayButtonsEnabled(false)
stopButton.isEnabled = true
case .notPlaying:
setPlayButtonsEnabled(true)
stopButton.isEnabled = false
}
}
func setPlayButtonsEnabled(_ enabled: Bool) {
snailButton.isEnabled = enabled
chipmunkButton.isEnabled = enabled
rabbitButton.isEnabled = enabled
vaderButton.isEnabled = enabled
echoButton.isEnabled = enabled
reverbButton.isEnabled = enabled
}
func showAlert(_ title: String, message: String) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: Alerts.DismissAlert, style: .default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
}
The screenshot of the error is in the link below.
Screenshot!

Answer 1

You can not declare var audioEngine = AVAudioEngine() inside an extension. Declare it inside PlaySoundsViewController class instead.
Extensions are meant to augment behaviours, not fundamentally change a class.
#source: Why can't you add stored properties to extensions?