myrickchow32

class AppDelegate: UIResponder, UIApplicationDelegate {
  func applicationDidEnterBackground(_ application: UIApplication) {
    // AVSpeechSynthesizer will be automatically stopped with a smooth volume reduction
    // The parameter of stopping the speech is AVSpeechBoundary.immediate
    print("applicationDidEnterBackground")
  }
  
  func applicationDidBecomeActive(_ application: UIApplication) {
    // AVSpeechSynthesizer will be automatically resumed
    print("applicationDidBecomeActive")

myrickchow32

var avSpeechSynthesizer: AVSpeechSynthesizer!

override func viewWillDisappear(_ animated: Bool) {
  super.viewWillDisappear(animated)
  avSpeechSynthesizer.stopSpeaking(at: .immediate)
}

myrickchow32

class AVFoundataionDemoViewController: BaseViewController {
  let avSpeechSynthesizer = AVSpeechSynthesizer()
  override func viewDidLoad() {
      super.viewDidLoad()  
      avSpeechSynthesizer.delegate = self
  }
}

extension AVFoundataionDemoViewController: AVSpeechSynthesizerDelegate {
  func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didStart utterance: AVSpeechUtterance) {

myrickchow32

import AVFoundation

let avSpeechSynthesizer = AVSpeechSynthesizer()
avSpeechSynthesizer.delegate = self

// Session 1 --- AVSpeechUtterance: 7 Parameters of synthesized speech 
let utterance = AVSpeechUtterance(string: "Hello world")
utterance.voice = ... 
utterance.rate = ...
utterance.pitchMultiplier = ...

myrickchow32

/* 
  Pitch multiplier range: 0.5 to 2.0
  Default value: 1.0
*/
let utterance = AVSpeechUtterance(string: "Hello world")
utterance.pitchMultiplier = 1.0

myrickchow32

/*
   Range: 0.0 - 1.0
   AVSpeechUtteranceMinimumSpeechRate: 0.0
   AVSpeechUtteranceMaximumSpeechRate: 1.0
   AVSpeechUtteranceDefaultSpeechRate: 0.5
 */
let utterance = AVSpeechUtterance(string: "Hello world")
utterance.rate = 0.5 

myrickchow32

let utterance = AVSpeechUtterance(string: "Hello world")
utterance.volume = 0.5 // Range: 0.0 - 1.0 ; A relative volume to the device volume

myrickchow32

let utterance = AVSpeechUtterance(string: "Hello world")

// Method 1: Directly by identifier
utterance.voice = AVSpeechSynthesisVoice(identifier: "com.apple.ttsbundle.Karen-compact")

// Method 2: By langauge code
utterance.voice = AVSpeechSynthesisVoice(language: "en-AU") 

myrickchow32

let speechVoices = AVSpeechSynthesisVoice.speechVoices()
speechVoices.forEach { (voice) in
  print("**********************************")
  print("Voice identifier: \(voice.identifier)")
  print("Voice language: \(voice.language)")
  print("Voice name: \(voice.name)")
  print("Voice quality: \(voice.quality.rawValue)") // Compact: 1 ; Enhanced: 2
}

/*

myrickchow32

let utterance = AVSpeechUtterance(string: "Hello world")