StateTriggerToggleGallery.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d"
             x:Class="Xamarin.Forms.Controls.GalleryPages.VisualStateManagerGalleries.StateTriggerToggleGallery"
             Title="StateTriggerToggle Gallery">
    <ContentPage.Resources>
        <ResourceDictionary>

            <Style x:Key="StateTriggerGridStyle" TargetType="Grid">
                <Setter Property="VisualStateManager.VisualStateGroups">
                    <VisualStateGroupList>
                        <VisualStateGroup>
                            <VisualState x:Name="Wide">
                                <VisualState.StateTriggers>
                                    <StateTrigger IsActive="{Binding ToggleState}"/>
                                </VisualState.StateTriggers>
                                <VisualState.Setters>
                                    <Setter Property="BackgroundColor" Value="Green" />
                                </VisualState.Setters>
                            </VisualState>
                            <VisualState x:Name="Narrow">
                                <VisualState.StateTriggers>
                                    <StateTrigger IsActive="{Binding ToggleStateInverted}"/>
                                </VisualState.StateTriggers>
                                <VisualState.Setters>
                                    <Setter Property="BackgroundColor" Value="Red" />
                                </VisualState.Setters>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateGroupList>
                </Setter>
            </Style>

        </ResourceDictionary>
    </ContentPage.Resources>
    <ContentPage.Content>
        <Grid
             Style="{StaticResource StateTriggerGridStyle}">
            <Frame
                HorizontalOptions="Center"
                VerticalOptions="Center"
                BackgroundColor="White"
                CornerRadius="12"
                Margin="24">
                <StackLayout
                    Orientation="Horizontal">
                    <CheckBox 
                        x:Name="CheckBox"
                        IsChecked="{Binding ToggleState, Mode=TwoWay}"
                        VerticalOptions="Center"/>
                    <Label
                        Text="Checked/Uncheck the CheckBox to modify the Grid BackgroundColor"
                        VerticalOptions="Center"/>
                </StackLayout>
            </Frame>
        </Grid>
    </ContentPage.Content>
</ContentPage>