Windows Universal无法在C＃中引用XAML控件？

Question

This seems like it wouldn't be much of an issue, but for whatever reason I created a simple rectangle in XAML and now can't reference it to change it programatically at runtime. What it's supposed to do is check whether one of the country panels has been selected and if one of the fields for a selected country matches the name of the hub section, it will highlight that rectangle at the bottom of the hub section to indicate to the user that the hub section is selected for as long as it is selected for. I can reference the hub sections themselves just fine, but I can't access the child object that is the rectangle. Here's the XAML for one of the hub sections first:

        <HubSection x:Name="China" Width="440" Height="460" Background="#FF343434" Header="China" IsHeaderInteractive="True" Tapped="{x:Bind HubSectionTapped}" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="50,0,0,0">
            <DataTemplate>
                <Grid Height="460" Width="410" VerticalAlignment="Bottom" x:Name="ChinaBackground">
                    <Image Source="Assets/chinaFlag.bmp" x:Name="ChinaFlag"/>
                    <Rectangle x:Name="ChinaSelected_Rect" Width="410" Height="30" VerticalAlignment="Bottom" Fill="BlueViolet" Opacity="0"/>
                </Grid>
            </DataTemplate>
        </HubSection>

and here's the code behind it:

    private void Timer_SelectionIndicator(object sender, object e)
    {
        if (currentCountry1 == "China" || currentCountry2 == "China")
        {
            //this line is the one that throws an error:
            //it says it needs an object reference to the rectangle, but...
            //I don't need a reference to reference the hub section itself... why?
            ChinaSelected_Rect.Opacity = 100;
        }
     }

Answer 1

You cant because its a DataTemplate . You will have to use Databindings.

I had a link to a very good tutorial site but its down. But, a quick google search you can find some very good examples.

Channel 9 - Part 17 - Understanding Data Binding, Data Sources and Data Contexts

Data binding in depth