UWP TextBox滚动至末尾

private void TextBoxScrollToEnd(TextBox textBox){
    var grid = (Grid)VisualTreeHelper.GetChild(textBox, 0); 
    for (var i = 0; i <= VisualTreeHelper.GetChildrenCount(grid) - 1; i++) 
    { 
            object obj = VisualTreeHelper.GetChild(grid, i); 
            if (!(obj is ScrollViewer)) continue; 
            ((ScrollViewer)obj).ChangeView(0.0f, ((ScrollViewer)obj).ExtentHeight, 1.0f); 
            break; 
        } 
    }
}