等待函数完成加载到 Xamarin Forms

Question

我正在加载一个在 App.xlm.cs 中翻译许多句子的函数，然后在为我的 MainPage 充电之后。

问题是我的函数没有完成加载并显示 MainPage。

如何确保我的函数会被加载？

这是我在 App.Xml.cs 中的函数：

public async void SetLeafLanguage() // here is the function I would like to wait before display the MainPage
{
        var phoneLanguage = "fr";// CultureInfo.CurrentUICulture.TwoLetterISOLanguageName;

        // transversal
        var WarningConnexionText = await MicosoftTranslater.TranslateText("this the first text", phoneLanguage);

        // Test page 
        var NumberOfWords = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);


        var ExerciceTitle = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        var AnswerPlaceHolder = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        var LabelNumberOfWordToTranslate = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        // parameter labels
        var AboutUstext = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

}

public void  GetUserOnData()
{
    SetLeafLanguage();
    MainPage = new MainPage();
}

public App ()
{
    InitializeComponent();
    GetUserOnData();
}

Answer 1

您需要将方法的返回类型设为Task 而不是void。

您应该始终避免使用async void 方法。参见微软的Async/Await - Best Practices

把你的代码改成这样：

public async Task SetLeafLanguage() // here is the function I would like to wait before display the MainPage
{
        var phoneLanguage = "fr";// CultureInfo.CurrentUICulture.TwoLetterISOLanguageName;

        // transversal
        var WarningConnexionText = await MicosoftTranslater.TranslateText("this the first text", phoneLanguage);

        // Test page 
        var NumberOfWords = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);


        var ExerciceTitle = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        var AnswerPlaceHolder = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        var LabelNumberOfWordToTranslate = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

        // parameter labels
        var AboutUstext = await MicosoftTranslater.TranslateText("this the second text", phoneLanguage);

}

public async Task GetUserOnData()
{
    await SetLeafLanguage();
    MainPage = new MainPage();
}

public App ()
{
    InitializeComponent();
    GetUserOnData();
}

不同之处在于，现在SetLeafLanguage 和GetUserOnData 两种方法都是async Task 类型。这意味着您可以简单地使用awaitSetLeafLanguage 方法。当你await它时，这意味着你将等待方法返回一些东西，然后你可以确定它已经完成了处理。

您可以在此处阅读有关异步返回类型的更多信息 - Async Return Types (C#)