How to use Xaml inheritance in WinUI 3? - xaml

Question

Judging from answers like this it looks like xaml inheritance works for WPF and UWP.
Does it work for WinUI 3?
Using code like this:
<local:YourBaseClass x:Class="MyApp.ChildClass"
...
xmlns:local="clr-namespace:MyApp">
</local:YourBaseClass>
I get the error:
Error WMC0001 Unknown type 'YourBaseClass' in XML namespace 'clr-namespace:MyApp'

Answer 1

Does it work for WinUI 3?
Yes. It almost exactly the same.
Create the base class that inherits from Microsoft.UI.Xaml.Window:
public class YourBaseClass : Microsoft.UI.Xaml.Window
{
public YourBaseClass() : base()
{
Title = "Title...";
}
}
Modify MainWindow.xaml.cs to inherit from the new base class:
public sealed partial class MainWindow : YourBaseClass
{
public MainWindow()
{
this.InitializeComponent();
}
private void myButton_Click(object sender, RoutedEventArgs e)
{
myButton.Content = "Clicked";
}
}
Modify the root element in MainWindow.xaml:
<local:YourBaseClass
x:Class="WinUI3App.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:WinUI3App"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
<Button x:Name="myButton" Click="myButton_Click">Click Me</Button>
</StackPanel>
</local:YourBaseClass>