swift - AVSpeechSynthesiser 窃听 ViewDidLoad 功能

Question

每当我导航到这个 View Controller 时，viewDidLoad 中的 speakText() 函数出于某种原因不起作用，并且 View Controller 需要很长时间才能加载(当我删除该行时情况并非如此)。在该行上方，文本标签的文本设置为要说出的字符串，并且工作正常。每次调用 recordTapped 时，语音合成都会完美运行。但是，它似乎在 viewDidLoad 中不起作用。

更新 在分配语音合成器的 View Controller 委托(delegate)并异步运行函数后，我做了一些更多的测试。但是，它不起作用。我将 View Controller 设置为初始 View Controller ，但它仍然不起作用，所以这不是导航问题，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

正如我在评论中所说，多线程工作。刚刚测试了自己。下面的工作代码，请测试并确认。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)
    }
}

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