UWP [Xaml]如何访问Button内的元素

Question

How to change txtPIN.Text value in C# code behind after UserControl was initialized.

Here is XAML

<Button x:Name="btn_pin" Content="Change PIN" Click="button_Click" Foreground="White">
            <Button.Template>
                <ControlTemplate TargetType="Button">
                    <StackPanel  Orientation="Horizontal" VerticalAlignment="Center">
                        <Image Source="/Assets/images/settings/lock.png" Stretch="UniformToFill" Width="16" Height="16"/>
                        <TextBlock x:Name="txtPin" Text="Change PIN" Foreground="White" />
                    </StackPanel>
                </ControlTemplate>
            </Button.Template>
        </Button>

and C#

public MyUserControl()
    {
        this.InitializeComponent();
        this.btn_pin.??????????
    }

Answer 1

You're not doing it the right way, just fix your xaml (I changed the Text binding of your TextBlock):

<Button x:Name="btn_pin" Content="Change PIN" Click="button_Click" Foreground="White">
            <Button.Template>
                <ControlTemplate TargetType="Button">
                    <StackPanel  Orientation="Horizontal" VerticalAlignment="Center">
                        <Image Source="/Assets/images/settings/lock.png" Stretch="UniformToFill" Width="16" Height="16"/>
                        <TextBlock x:Name="txtPin" Text="{TemplateBinding Content}" Foreground="White" />
                    </StackPanel>
                </ControlTemplate>
            </Button.Template>
        </Button>

and every time you want to change the text, change the Content of the button like this:

    public MainPage()
    {
        this.InitializeComponent();
        btn_pin.Content = "New label";
    }