TreeViewTestPage.xaml

<!-- Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT License. See LICENSE in the project root for license information. -->
<Page
    x:Class="TestAppCX.TreeViewTestPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:TestAppCX"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:controls="using:Microsoft.UI.Xaml.Controls"
    mc:Ignorable="d">

    <StackPanel Padding="20">
        <controls:TreeView
            x:Name="TestTreeView"
            HorizontalAlignment="Left"
            Width="400" Height="400"
            ItemsSource="{x:Bind Items}">
            <controls:TreeView.ItemTemplate>
                <DataTemplate x:DataType="local:TreeViewData">
                    <controls:TreeViewItem
                        ItemsSource="{x:Bind Children}"
                        Content="{x:Bind Content}" />
                </DataTemplate>
            </controls:TreeView.ItemTemplate>
        </controls:TreeView>

        <Button Content="ReplaceAll" Click="ReplaceAll_Click" />
        <Button Content="Clear" Click="Clear_Click" />
    </StackPanel>
</Page>