AVSpeechSynthesiser 窃听 ViewDidLoad 函数

Question

每当我导航到这个视图控制器时，viewDidLoad 中的 speakText() 函数由于某种原因不起作用，并且视图控制器需要很长时间才能加载（当我删除该行时不是这种情况）。在该行上方，文本标签的文本设置为要朗读的字符串，并且工作正常。每次调用recordTapped，语音合成都能完美运行。但是，它似乎在viewDidLoad 中不起作用。

更新在分配语音合成器的视图控制器委托并异步运行该功能后，我做了更多测试。但是，它不起作用。我将视图控制器设置为初始视图控制器，它仍然不起作用，所以导航不是问题，加载时间仍然很长。

import UIKit
import AVFoundation

class StartViewController: UIViewController, AVAudioRecorderDelegate {

    @IBOutlet weak var questionLabel: UILabel!
    @IBOutlet weak var recordButton: UIButton!
    let synth = AVSpeechSynthesizer()
    var myUtterance = AVSpeechUtterance(string: "")
    var number = 0

    override func viewDidLoad() {
        super.viewDidLoad()
        synth.delegate? = self as! AVSpeechSynthesizerDelegate
        number = 0
        DispatchQueue.global(qos: .userInitiated).async       {self.speakText(int: number)}
        self.number = self.number + 1
    }

    @IBAction func recordTapped(_ sender: UIButton) {
        speakText(int: number)
        number = number + 1
    }

    func speakText(int: Int) {

    myUtterance = AVSpeechUtterance(string: "the number is \(int)")
    myUtterance.voice = AVSpeechSynthesisVoice(language: "en-AU")
    synth.speak(myUtterance)

    }

}

Answer 1

正如我在 cmets 中所说，多线程有效。刚刚测试了自己。工作代码如下，请测试确认。依靠单独的线程进行语音总是好的。

import UIKit
import AVFoundation

class ViewController: UIViewController {

    @IBOutlet weak var questionLabel: UILabel!
    @IBOutlet weak var recordButton: UIButton!

    var number = 0

    @IBAction func recordTapped(_ sender: UIButton) {
        questionLabel.text = "\(number)"
        speakTest(int: number)
        number += 1
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        number = 0
        questionLabel.text = "\(number)"
        DispatchQueue.global(qos: .userInitiated).async {
            self.speakTest(int: self.number)
        }
//        speakTest(int: number)

        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func speakTest(int: Int) {
        let utterance = AVSpeechUtterance(string: "Number is \(int)")
        let synth = AVSpeechSynthesizer()
        synth.speak(utterance)
    }
}

Plus，要在视图出现时调用 Speech，请从 viewWillAppear() 或 viewDidAppear() 调用它，而不是从 viewDidLoad() 调用，因为后者在应用程序处于前台时调用一次。