Xamarin Forms 本机视图中的 RadioGroup [英] RadioGroup in Xamarin Forms Native Views

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

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"

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IT屋！