How to get all the textBoxes in the UserControl added into GridView - winrt-xaml

Question

On the Page, I add UserControl into GridView dynamically. So, each UserControl can contain different kind of controls ( TextBox, CheckBox, Radio Button)
say , the name of UserControl is : UserForm.
problem :
How to get a collection of control using VisualTreeHelper and check if textBox is empty.
I found a code similiar to this problem and modified it but not working.
I dont know what this means and if this is required?
list.AddRange(AllTextBoxes(child))
Should I use MyList.Select() or MyList.Where() ?
void FindTextBoxes()
{
List <TextBox> MyList = AllTextBoxes(UserForm);
var count = MyList.Where(x= > if(string.IsEmptyOrNull(x.Text));
}
List <TextBox> AllTextBoxes(DependencyObject parent)
{
var list = new List <TextBox>();
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
if (child is TextBox)
list.Add(child as TextBox);
list.AddRange(AllTextBoxes(child));
}
return list;
}

Answer 1

Here's what I use.
void MainPage_Loaded(object sender, RoutedEventArgs e)
{
var textBoxes = AllChildren(MyGridView).Where(x => x is TextBox);
}
public IEnumerable<Control> AllChildren(DependencyObject parent)
{
for (int index = 0; index < VisualTreeHelper.GetChildrenCount(parent); index++)
{
var child = VisualTreeHelper.GetChild(parent, index);
if (child is Control)
yield return child as Control;
foreach (var item in AllChildren(child))
yield return item;
}
}
Best of luck!