Xamarin Forms 本机视图中的 RadioGroup

问题描述

我有以下几行 XAML，它们在 Xamarin 表单中使用本机视图:

I have the following lines of XAML that utilises Native Views in Xamarin Forms:

        <androidWidget:RadioGroup x:Arguments="{x:Static formsAndroid:Forms.Context}">
            <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Click="RadioButton1Clicked"/>
            <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Click="RadioButton2Clicked"/>
            <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Click="RadioButton3Clicked"/>
            <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Click="RadioButton4Clicked"/>
        </androidWidget:RadioGroup>

但是，抛出以下异常:无法设置androidWidget:RadioGroup的内容，因为它没有ContentPropertyAttribute"

However, the following exception is thrown: "Can not set the content of androidWidget:RadioGroup as it doesn't have a ContentPropertyAttribute"

只是想知道是否有人可以帮助我找到与 RadioButton 相关的 RadioGroup 的正确 XAML 布局?

Just wondering if anyone could help me find the correct XAML layout for the RadioGroup in relation to the RadioButtons?

干杯

推荐答案

并非所有原生视图都可以直接在 xaml 中使用.RadioGroup 就是其中之一.

Not all native views can be used in xaml directly. RadioGroup is one of them.

要在您的 Xaml 中使用它，您需要按照以下步骤操作:

To use it in your Xaml, you need to follow the below steps:

1. 在 YourProject.Droid 中创建一个自定义的 RadioGroup 控件:

1. In YourProject.Droid create a custom RadioGroup control:

public class MyRadioGroup:RadioGroup
{
    //Every native control in xaml will be wrapped in NativeViewWrapper, so we want to pass a NativeViewWrapper list here
    IList<NativeViewWrapper> items;
    public IList<NativeViewWrapper> ItemsSource
    {
        get {
            items.Clear();
            for (int i = 0; i < this.ChildCount; i++)
            {
                items.Add(new NativeViewWrapper(this.GetChildAt(i)));
            }
            return items;
        }
        set {
            //xaml compiler will call this setter
            if (items != value)
            {
                items = value;
                this.RemoveAllViews();
                foreach (NativeViewWrapper wrapper in items)
                {
                    this.AddView(wrapper.NativeView);
                }
            }
        }
    }
    public MyRadioGroup(Context context) : base(context)
    {
        items = new List<NativeViewWrapper>();
    }
}

在您的 pcl 库中添加必要的命名空间:

In your pcl library add necessary namespaces:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
        xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
        ...
        xmlns:androidWrapper="clr-namespace:Xamarin.Forms.Platform.Android;assembly=Xamarin.Forms.Platform.Android;targetPlatform=Android"
        xmlns:androidWidget="clr-namespace:Android.Widget;assembly=Mono.Android;targetPlatform=Android"
        xmlns:androidLocal="clr-namespace:NativeSwitch.Droid;assembly=NativeSwitch.Droid;targetPlatform=Android"
        xmlns:formsAndroid="clr-namespace:Xamarin.Forms;assembly=Xamarin.Forms.Platform.Android;targetPlatform=Android"
xmlns:local="clr-namespace:NativeSwitch"
...">

在您的 xaml 页面中引用自定义 MyRadioGroup:

<StackLayout Margin="20">
    <androidLocal:MyRadioGroup x:Arguments="{x:Static formsAndroid:Forms.Context}" >
        <androidLocal:MyRadioGroup.ItemsSource>
            <x:Array Type="{x:Type androidWrapper:NativeViewWrapper}">
                <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Text="Scale1" />
                <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Text="Scale2" />
                <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Text="Scale3" />
                <androidWidget:RadioButton x:Arguments="{x:Static formsAndroid:Forms.Context}" Text="Scale4" />
            </x:Array>
        </androidLocal:MyRadioGroup.ItemsSource>
    </androidLocal:MyRadioGroup>
</StackLayout>

您可以在此处找到完整的演示.

You can find a complete demo here.

类似的官方教程请参考子类化原生视图

有关在 Xaml 中传递参数，请参阅传递参数Xml

For passing arguments inside Xaml, please refer to Passing Arguments in Xaml

这篇关于Xamarin Forms 本机视图中的 RadioGroup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！