如何在iOS上停止/切断Xamarin Essentials文字转语音以开始新的演讲

Question

在启动Xamarin.Forms时，无法停止xamarin要点文本到语音转换以启动新的文本到语音“ SpeakAsync”调用。

使用此应用程序作为“练习电话”的模拟话务员，我想在用户挂断电话时切断说“ hello this is ....”的话务员，并使用语音异步开始说“这通话结束后，通话立即结束”

await TextToSpeech.SpeakAsync("Hello this is the operator, thank you for calling, how can I help you?"
    , SpeechTokenSource.Token);

目前这可以在android上按预期工作

public void CancelSpeech()
{
    if (SpeechTokenSource?.IsCancellationRequested ?? true)
    return;

    SpeechTokenSource.Cancel();
}

尝试使用文档（ https://docs.microsoft.com/zh-cn/xamarin/essentials/text-to-speech ）中列出的取消令牌，但是我无法获得当前的“ SpeakAsync”语音以立即停止播放iOS，或下一个讲语音同步命令，一旦取消初始的文本转语音，即可在iOS上开始讲文本。

   CancelSpeech();

   IsCallActive = false;
   DialedText = null;

   //Reset speech cancellation token
   SpeechTokenSource = new CancellationTokenSource();

   await TextToSpeech.SpeakAsync("This call has ended. Goodbye."
   , SpeechTokenSource.Token);

在iOS输出中记录的错误：“ [[AXTTSCommon] _BeginSpeaking：无法开始播放”

我有什么想念的吗？ 如何取消当前正在播放的文本转语音并在此后立即开始下一个语音？

编辑：

这只需单击一个按钮即可完成（取消当前语音并开始“此通话已结束”语音）

Answer 1

我无法重现您的问题。

以下代码使用Xamarin.Essentials v1.3.0和Xamarin.Forms v4.2.0.709249在iOS和Android上均可使用。

轻按“ speakButton ，将说出语音；当轻按“ cancelButton轻按“ cancelButton时，语音将停止。

在iOS和Android上取消SpeakAsync时有一个区别：

• 在iOS上，当前正在说的单词已完成，然后停止说话
• 在Android上，当前正在说出的单词会被切断，并且说话会停止

样例代码

完整的示例应用程序可以在这里找到： https : //github.com/brminnick/CancelTextToSpeechSample/tree/master

using System;
using System.Threading;
using Xamarin.Forms;

namespace CancelTextToSpeechSample
{
    public class App : Application
    {
        public App()
        {
            MainPage = new CancelSpeakPage();
        }

        class CancelSpeakPage : ContentPage
        {
            const string _spokenText = "Oh, supercalifragilisticexpialidocious! Even though the sound of it, Is something quite atrocious, If you say it loud enough, You'll always sound precocious, Supercalifragilisticexpialidocious!";

            CancellationTokenSource _speakButtonCancellationTokenSource;

            public CancelSpeakPage()
            {
                var speakButton = new Button { Text = "Sing" };
                speakButton.Clicked += HandleSpeakButtonClicked;

                var cancelButton = new Button { Text = "Cancel Song" };
                cancelButton.Clicked += HandleCancelButtonClicked;

                Content = new StackLayout
                {
                    VerticalOptions = LayoutOptions.Center,
                    HorizontalOptions = LayoutOptions.Center,

                    Children =
                    {
                        speakButton,
                        cancelButton
                    }
                };
            }

            void HandleCancelButtonClicked(object sender, EventArgs e)
            {
                _speakButtonCancellationTokenSource?.Cancel();
            }

            async void HandleSpeakButtonClicked(object sender, EventArgs e)
            {
                if (_speakButtonCancellationTokenSource?.IsCancellationRequested is false)
                    _speakButtonCancellationTokenSource.Cancel();

                _speakButtonCancellationTokenSource = new CancellationTokenSource();
                await Xamarin.Essentials.TextToSpeech.SpeakAsync(_spokenText, _speakButtonCancellationTokenSource.Token);
            }
        }
    }
}