เราจะได้ sender จาก PointerEventHandler ซึ่งเราสามารถนำมันมาหา index ได้ครับ ในตัวอย่างผมแสดงสามวิธีง่ายๆ: 1. เราอาจจะใช้ DataContext 2. หรือใช้ name หรือ ค่าอื่นๆ 3. หา index จาก array ที่เก็บ sender

MainPage.cs

public sealed partial class MainPage : Page
{
    UIElement[] _uiElements;

    public MainPage()
    {
        this.InitializeComponent();
        var uiElements = new List<UIElement>();
        for (int i = 0; i < 10; i++)
        {
            var txtBlock = new TextBlock 
            { 
                FontSize = 20.0d, 
                Text = "TEXT "+i,
                DataContext = i,
                Name = "txtBlock-" + i,
            };
            txtBlock.PointerPressed += txtBlock_PointerPressed;
            stackPanel.Children.Add(txtBlock);
            uiElements.Add(txtBlock);                
        }

        _uiElements = uiElements.ToArray();
    }

    void txtBlock_PointerPressed(object sender, PointerRoutedEventArgs e)
    {            
        // get from data context         
        int? txtBlockNum = ((FrameworkElement)sender).DataContext as int?;

        // get from name
        string txtBlockName = ((FrameworkElement)sender).Name;
        string txtBlockNum2 = txtBlockName.Substring(txtBlockName.IndexOf("-")+1);

        // get from _uiElements array
        int txtBlockNum3 = Array.FindIndex(_uiElements, txtBlck => txtBlck == sender);

        txtBox.Text = txtBlockNum.Value.ToString() + " "
            + txtBlockNum2 + " "
            + txtBlockNum3;
    }

    /// <summary>
    /// Invoked when this page is about to be displayed in a Frame.
    /// </summary>
    /// <param name="e">Event data that describes how this page was reached.  The Parameter
    /// property is typically used to configure the page.</param>
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
    }
}