如何將綁定上下文標籤值保存爲xamarin表單中的字符串

Question

ListView listView = new ListView(); 
listView.ItemTemplate = new DataTemplate(typeof(CustomVeggieCell)); 
listView.ItemsSource = sample; 
Content = new StackLayout 
{ 
    Children ={ 
     listView, 
    } 
}; 


public class CustomVeggieCell : ViewCell 
{ 
public CustomVeggieCell() 
{ 
     var image = new Image(); 
     var typeLabel = new Label { }; 


     typeLabel.SetBinding(Label.TextProperty, new Binding("contact")); 

     var string = typeLabel.Text; 

     if (typeLabel.Text == "Send") 
     { 
      image.Source = "Send.png"; 
     } 
     else 
     { 
      image.Source = "draft.png"; 
     } 


     var horizontalLayout = new StackLayout(); 
     horizontalLayout.Children.Add(image); 


     View = horizontalLayout; 

    } 
} 

我已經使用Xamarin表單中的Json Web服務響應創建了一個listview。我需要根據值顯示圖像。 綁定值無法存儲在字符串中。它總是返回null。我想存儲綁定標籤文本。何實現這一目標？

Answer 1

可以使用的IValueConverter

喜歡的東西

public class CustomVeggieCell : ViewCell 
{ 
    public CustomVeggieCell() 
    { 
     var image = new Image(); 

     image.SetBinding(Image.SourceProperty, new Binding("contact", BindingMode.Default, new ConvertTextToSource())); 

     var horizontalLayout = new StackLayout(); 
     horizontalLayout.Children.Add(image); 


     View = horizontalLayout; 

    } 

} 

然後轉換

 public class ConvertTextToSource : IValueConverter 
     { 

      #region IValueConverter implementation 

      public object Convert (object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
      { 
       if (value != null && value is string) { 

        string text = ((string)value); 

        if (text == "Send") 
        { 
         return "Send.png"; 
        } 
        else 
        { 
         return "draft.png"; 
        } 
       } 
       return ""; 
      } 

      public object ConvertBack (object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
      { 
       throw new NotImplementedException(); 
      } 

      #endregion 
     } 

它應該工作