CollectionView SelectedItem在Xamarin表单中未突出显示

<?xml version="1.0" encoding="UTF-8"?>
<ResourceDictionary xmlns="http://xamarin.com/schemas/2014/forms"
                    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                    xmlns:local="clr-namespace:YourNamespace">

    <Style x:Key="CollectionViewItemSelectedStyle" TargetType="ContentView">
        <Setter Property="VisualStateManager.VisualStateGroups">
            <VisualStateGroupList>
                <VisualStateGroup x:Name="CommonStates">
                    <VisualState x:Name="Normal" />
                    <VisualState x:Name="Selected">
                        <VisualState.Setters>
                            <Setter Property="BackgroundColor" Value="LightBlue" />
                            <Setter Property="TextColor" Value="White" />
                        </VisualState.Setters>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateGroupList>
        </Setter>
    </Style>

    <Style TargetType="CollectionView">
        <Setter Property="ItemTemplate">
            <Setter.Value>
                <DataTemplate>
                    <ContentView Style="{StaticResource CollectionViewItemSelectedStyle}">
                        <!-- 在此处定义CollectionView的Item模板 -->
                    </ContentView>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.YourPage">

    <ContentPage.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <local:CollectionViewItemSelectedStyle />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </ContentPage.Resources>

    <!-- 在此处定义页面的内容 -->

</ContentPage>