C＃UWP XAML检查XAML中是否存在

Question

Im working on building different layouts for my app. If the app runs in landscape I want to be able to show a map on one side on the screen, but not show a map if in portrait. I'm using VisualStateManager to help me do this.

I need to run some code in c# on the map control I have named "MyMap" but how can I make that bit of the code run only when the map is present - in other words is there a way I can check if it exists in the XAML?

Without the map any code referring to MyMap of course throws an error - is this the best way of going about this or am I missing a better way?

EDIT

I'm using an approach similar to the below to work out what template should be used depending on the MinWindowWidth. So MyMap will only exist in the LargeTemplate etc

<Page.Resources>
    <DataTemplate x:Key="SmallTemplate">
        <Grid>
            <Border Background="LightGray" Height="100" Width="100">
                <TextBlock Text="{Binding Text}" 
                          FontSize="48" Foreground="Green" />
            </Border>
        </Grid>
    </DataTemplate>
    <DataTemplate x:Key="LargeTemplate">
        <Grid>
            <Border Background="LightGray" Height="200" Width="200">
                <TextBlock Text="{Binding Text}" 
                          FontSize="48" Foreground="Green" />
            </Border>
        </Grid>
    </DataTemplate>
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <VisualStateManager.VisualStateGroups>
        <VisualStateGroup>
            <VisualState x:Name="Small">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="0" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="MyGridView.ItemTemplate" Value="{StaticResource SmallTemplate}" />
                </VisualState.Setters>
            </VisualState>
            <VisualState x:Name="Large">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="720" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="MyGridView.ItemTemplate" Value="{StaticResource LargeTemplate}" />
                </VisualState.Setters>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups> 
    <GridView Name="MyGridView"/>
</Grid>

Answer 1

Add an x:Name to your VisualStateGroup eg. AdaptiveVisualStateGroup , after that you can check for the CurrentState in your code like this: AdaptiveVisualStateGroup.CurrentState

If the CurrentState equals Large or whatever the name is your VisualState where you have your map, you can run the code that references MyMap , otherwise you just skip it