无法在Xamarin中设置SwitchCell的绑定

问题描述

我正在尝试创建带有元素列表的SwitchCell.尽管由于stackoverflow我找到了使用普通字符串列表的方法，但是当我尝试将Cell-Properties绑定到自制结构时，我还是找不到我做错的事情.

I am trying to create a SwitchCell with a list of Elements.Eventhough I found out how to do that with a plain string-List thanks to stackoverflow I can't find out what I'm doing wrong when I try to bind the Cell-Properties to a self-made struct.

这是我的代码:

public class RestaurantFilter
{
    public List<FilterElement> Types;

    public RestaurantFilter(List<string> types)
    {
        Types = new List<FilterElement>();

        foreach (string type in types)
            Types.Add(new FilterElement { Name = type, Enabled = false });
    }
}

public struct FilterElement
{
    public string Name;
    public bool Enabled;
}

public FilterPage()
{
    List<string> l = new List<string>(new string[] { "greek", "italian", "bavarian" });
    RestaurantFilter filter = new RestaurantFilter(l);

    ListView types = new ListView();
    types.ItemTemplate = new DataTemplate(() =>
    {
        var cell = new SwitchCell();
        cell.SetBinding(SwitchCell.TextProperty, "Name");
        cell.SetBinding(SwitchCell.IsEnabledProperty, "Enabled");
        return cell;
    });
    types.ItemsSource = filter.Types;

    Content = types;

}

但是应用程序中的SwitchCell不会显示名称或布尔值.

But the SwitchCell's in the Application do not show the Name or the Boolean.

推荐答案

关于IsEnabledProperty-似乎存在IsEnabled属性的已知错误，该错误将在Xamarin.Forms 2.3.0-pre1版本中修复.与您的情况有关:

About the IsEnabledProperty - there seem to be a knonw bug with the IsEnabled property that will be fixed in the Xamarin.Forms 2.3.0-pre1 release so that might be related to your case:

https://bugzilla.xamarin.com/show_bug.cgi?id=25662

关于Name属性-尝试将您的FilterElement结构更改为具有如下属性和PropertyChangedEventHandler的类，它将起作用:

About the Name property - try changing your FilterElement struct to a class with properties and PropertyChangedEventHandler like this and it will work:

public class FilterElement
{
    public event PropertyChangedEventHandler PropertyChanged;

    private string _name;
    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;

            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("Name"));
            }
        }
    }

    private bool _enabled;
    public bool Enabled
    {
        get { return _enabled; }
        set
        {
            _enabled = value;

            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("Enabled"));
            }
        }
    }       
}

这样，您将能够更新类型"列表，它将自动更新ListView.

That way you will be able to update the Types list and it will automatically update the ListView.

顺便说一句，如果要基于ViewModel打开或关闭过滤器(不启用或禁用过滤器)，则需要使用OnProperty进行绑定:

By the way, if you want to turn the filter on or off based on your ViewModels (not enable or disable it), you need to use the OnProperty for the binding:

https://developer.xamarin.com/api/field/Xamarin.Forms.SwitchCell.OnProperty/

这篇关于无法在Xamarin中设置SwitchCell的绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！