MainPage.xaml

<Page
    x:Class="SampleTest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:SampleTest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:wgt="using:Microsoft.Toolkit.Graph.Controls"
    xmlns:graph="using:Microsoft.Graph"
    xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"
    xmlns:providers="using:Microsoft.Toolkit.Graph.Providers"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
    xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"><!-- Workaround for https://github.com/microsoft/microsoft-ui-xaml/issues/1286 -->
    <!-- 
        Initialize Graph Provider On Page Load 
    
        Register Client Id: https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-app
        
        After finishing the initial registration page, you will also need to add an additional redirect URI. 
        Click on "Add a Redirect URI" and check the https://login.microsoftonline.com/common/oauth2/nativeclient checkbox on that page. Then click "Save".
    -->
    <Interactivity:Interaction.Behaviors>
        <!--<providers:InteractiveProviderBehavior ClientId="YOUR_CLIENT_ID_HERE" Scopes="User.Read,User.ReadBasic.All,People.Read,Calendars.Read"/>-->
        <providers:MockProviderBehavior/>
    </Interactivity:Interaction.Behaviors>

    <Grid>
        <wgt:LoginButton VerticalAlignment="Top" HorizontalAlignment="Right"/>
        <StackPanel Margin="16,48">
            <wgt:PeoplePicker x:Name="PeopleChooser"/>
            <TextBlock Margin="0,8,0,0" FontWeight="Bold">Picked People:</TextBlock>
            <ItemsControl ItemsSource="{x:Bind PeopleChooser.ItemsSource}"
                          Margin="8,0,0,0">
                <ItemsControl.ItemTemplate>
                    <DataTemplate x:DataType="graph:Person">
                        <TextBlock Text="{x:Bind DisplayName}"/>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </StackPanel>
    </Grid>
</Page>