private void SearchBar_OnTextChanged(object sender, TextChangedEventArgs e)
{
CustomerView.BeginRefresh();
if (string.IsNullOrWhiteSpace(e.NewTextValue))
{
CustomerView.ItemsSource = Klanten;
}
else
{
CustomerView.ItemsSource = Klanten.Where(i => i.Name.Contains(e.NewTextValue));
}
CustomerView.EndRefresh();
}