UWP - Get ComboBox selected item

MainPage.xaml

<Page
    x:Class="UniversalAppTutorials.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UniversalAppTutorials"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <StackPanel 
        x:Name="stack_panel1" 
        Margin="50" 
        Orientation="Horizontal"
        Background="AliceBlue"
        Padding="50"
        >
        <ComboBox 
            x:Name="ComboBox1"
            SelectionChanged="ComboBox1_SelectionChanged"
            Margin="0,100,0,0"
            />
        <TextBlock
            x:Name="TextBlock1"
            Foreground="Crimson"
            FontFamily="MV Boli"
            FontSize="25"
            Text="Select a color from ComboBox."
            TextWrapping="WrapWholeWords"
            Margin="100,100,0,0"
            />
    </StackPanel>
</Page>
MainPage.xaml.cs

using Windows.UI.Xaml.Controls;


namespace UniversalAppTutorials
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();

            // Initialize a new string array
            string[] colors = {
                "Red",
                "Green",
                "Blue",
                "Yellow",
                "Snow",
                "Gold",
                "Forest Green",
                "Medium Sea Green"
            };

            // Specify the ComboBox item source
            ComboBox1.ItemsSource = colors;
        }

        private void ComboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            // Get the instance of ComboBox
            ComboBox comboBox = sender as ComboBox;

            // Get the ComboBox selected item text
            string selectedItems = comboBox.SelectedItem.ToString();

            // Finally, display the ComboBox selected item text to text block
            TextBlock1.Text = "Selected : " + selectedItems;
        }
    }
}