Do not use AVAudioSession on macOS

Application/ContentView.swift

@@ -107,7 +107,9 @@ struct ContentView: View {
  let auChannel: AUMessageChannel
  let langs: [(id: String, name: String)]
  let voices: [(id: String, name: String)]
+ #if os(iOS)
  let audioSession = AVAudioSession.sharedInstance()
+ #endif
  @State var synthText: String = "Hello"
  @State var langId: String = "gmw/en-US"
  @State var voiceId: String = ""
@@ -116,12 +118,14 @@ struct ContentView: View {
  init(audioUnit: AVAudioUnit) {
  self.audioUnit = audioUnit
  self.auChannel = audioUnit.auAudioUnit.messageChannel(for: "espeakData")
+ #if os(iOS)
  try? audioSession.setCategory(
  .playback,
  mode: .spokenAudio,
  policy: .default,
  options: [.duckOthers]
  )
+ #endif
  let res = self.auChannel.callAudioUnit?(["initHost":true])
  let langIds = (res?["langIds"] as? [String]) ?? []
  let langNames = (res?["langNames"] as? [String]) ?? []
@@ -161,8 +165,10 @@ struct ContentView: View {
  AVSpeechSynthesisProviderVoice.updateSpeechVoices()
  })
  .navigationTitle("eSpeak-NG")
+ #if os(iOS)
  .onAppear { try? audioSession.setActive(true) ; try? engine.start() }
  .onDisappear { engine.stop() ; try? audioSession.setActive(false) }
+ #endif
  .toolbar {
  NavigationLink(destination: {
  VoiceOverLangSelector(