如何从 Xamarin 中 App class 中的全局变量绑定到 Codebehind

Question

我正在尝试创建一个带有传统购物车图标的 NavigationPage TitleView，上面写着 (3) Items 等。所以全局 CartCount 变量在 App class 中声明。我的 CommonToolbarPage class 在所有 50 个页面的顶部布置了徽标、搜索按钮和购物车图标，就像互联网上的每个商店一样。我正在使用棱镜。

我想要的是绑定到 CartCount 的内容，以便 BadgeText 在 CartCount 更新时更新。

BadgeText = App.CartCount , // Jiberish

减少class

public class CommonToolbarPage : ContentPage
{

    public CommonToolbarPage()
    {
        //NavigationPage.SetHasBackButton(this, false);
        ShowDefaultTitle();
      //this.BindingContext=  new CommonToolbarPageViewModel(navigationService);

    }


    private void ShowDefaultTitle()
    {
        


        SfButton sfButton = new SfButton
        {
            CornerRadius = 4,
            HorizontalOptions = LayoutOptions.End,
            VerticalOptions = LayoutOptions.Center,
            Style = (Style)Application.Current.Resources["IconButtonStyle"],
            Text = (String)Application.Current.Resources["Cart"],
            FontFamily = "UIFontIcons",
            TextColor = Color.White,

            // Command = new Command(GoCart)
        };

        var Endlayout = new StackLayout
        {
            Orientation = StackOrientation.Horizontal,
            HorizontalOptions = LayoutOptions.EndAndExpand,

        };

        var imSfBadgeView = new SfBadgeView
        {
          
            BadgeText = App.Cart, // Jiberish 
            Margin = new Thickness(0, 0, 10, 0),
            Padding = new Thickness(0),
            WidthRequest = 40,
            // Content = sfButton,
            HorizontalOptions = LayoutOptions.EndAndExpand,
            VerticalOptions = LayoutOptions.Center,
            BackgroundColor = Color.Transparent,
            BadgeSettings = new BadgeSetting
            {
                BackgroundColor = (Color)Application.Current.Resources["PrimaryColor"],
                BadgeType = BadgeType.None,
                FontSize = 10,
                Stroke = (Color)Application.Current.Resources["Gray-White"],
                StrokeWidth = 1,
                Offset = new Point(-10, 10)
            }
        };
        Endlayout.Children.Add(imSfBadgeView);
       


         NavigationPage.SetTitleView(this, Endlayout);
    }

   
}

每个页面看起来像这样：

<?xml version="1.0" encoding="utf-8" ?>
<local1:CommonToolbarPage  xmlns:local1="clr-namespace:blaAppV1.Views.Templates" 
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:listview="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms"
 xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:prism="http://prismlibrary.com"
prism:ViewModelLocator.AutowireViewModel="True"
xmlns:local="clr-namespace:blaAppV1.Views;assembly=blaAppV1"
x:Class="blaAppV1.Views.Home">


  <StackLayout VerticalOptions="StartAndExpand" HorizontalOptions="Center">
    <Label Text="Home" VerticalOptions="Center" HorizontalOptions="Center" />
    <Button Text="Appliances" Command="{Binding Path=NavigateCommand}" CommandParameter="Appliances" />
</StackLayout>

Answer 1

您使用 SetBinding 在代码中创建绑定

myLabel.SetBinding(Label.TextProperty, "CartCount");
myLabel.BindingContext = App;

如何从 Xamarin 中 App class 中的全局变量绑定到 Codebehind

How to bind in Codebehind from a global variable in App class in Xamarin

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