How to maintain the scroll position of ListView after clearing the filter at runtime?

public class Behaviours: Behavior<SfListView>
{
   private SfListView listView;
   private SearchBar searchBar = null;
   ExtendedScrollView scrollview;
   double position;
   protected override void OnAttachedTo(BindableObject bindable)
   {
      listView = bindable as SfListView;
      searchBar = (bindable as SfListView).FindByName<SearchBar>("filterText");
      searchBar.TextChanged += SearchBar_TextChanged;
      scrollview = listView.GetScrollView();
      base.OnAttachedTo(bindable);
   }
 
   protected override void OnDetachingFrom(BindableObject bindable)
   {
      listView = null;
      searchBar = null;
      searchBar.TextChanged -= SearchBar_TextChanged;
      base.OnDetachingFrom(bindable);
   }
   
   private bool FilterContacts(object obj)
   {
      if (searchBar == null || searchBar.Text == null)
         return true;
 
      var contacts = obj as Contacts;
      if (contacts.ContactName.ToLower().Contains(searchBar.Text.ToLower())
                || contacts.ContactName.ToLower().Contains(searchBar.Text.ToLower()))
         return true;
      else
         return false;
   }
 
   private void SearchBar_TextChanged(object sender, TextChangedEventArgs e)
   {
      if (searchBar.Text != "")
         position = scrollview.ScrollY;
 
      searchBar = (sender as SearchBar);
      if (listView.DataSource != null)
      {
         this.listView.DataSource.Filter = FilterContacts;
         this.listView.DataSource.RefreshFilter();
      }
      if (searchBar.Text == "")
         listView.ScrollTo(position);
      else if (searchBar.Text == "")
         listView.ScrollTo(position);
   }
}