在Xamarin Forms C＃上设置后退按钮标题

Question

我对c＃和Xamarin很新，我刚遇到一个问题。我似乎无法在导航页面上设置后退按钮标题。我尝试过使用静态SetBackButtonTitle方法，但它似乎没有将后退按钮设置为我想要的标题'Test'，而是它给我'默认'标题，即“返回”。

        // The root page of your application
        var content = new ContentPage();


        var CompanyName = new Label();
        CompanyName.HorizontalTextAlignment = TextAlignment.Center;
        CompanyName.Text = "Test";

        var NextPage = new Button();
        NextPage.Text = "Next Page";
        NextPage.Font = Font.SystemFontOfSize(NamedSize.Large);
        NextPage.BorderWidth = 1;
        NextPage.HorizontalOptions = LayoutOptions.Center;
        NextPage.VerticalOptions = LayoutOptions.CenterAndExpand;

        var layout = new StackLayout();
        layout.VerticalOptions = LayoutOptions.CenterAndExpand;
        layout.Children.Add(CompanyName);
        layout.Children.Add(NextPage);

        content.Content = layout;

        var content2 = new ContentPage();

        var navigation = new NavigationPage(content);
        NavigationPage.SetHasBackButton(navigation,true);
        NavigationPage.SetBackButtonTitle(navigation,"Test");

        NextPage.Clicked += NextPageClicked;
        async  void NextPageClicked(object sender, EventArgs e)
        {
            await navigation.PushAsync(content2);
        }

        MainPage = navigation;



    }