public Students()
 {
     InitializeComponent();
     refreshCount++;
     BindingContext = StudentColl.GetStudentsWithGrouping();
     Icon           = "icon.png";
 }
        void OnRefreshing(object sender, EventArgs e)
        {
            ListView lv = (ListView)sender;

            refreshCount++;
            BindingContext  = StudentColl.GetStudentsWithGrouping();
            lv.IsRefreshing = false;
        }
 void OnSearch(object sender, TextChangedEventArgs e)
 {
     if (!String.IsNullOrEmpty(e.NewTextValue) && e.NewTextValue.Length > 2)
     {
         BindingContext = StudentColl.GetStudentsWithGrouping(e.NewTextValue);
     }
     else if (String.IsNullOrEmpty(e.NewTextValue))
     {
         BindingContext = StudentColl.GetStudentsWithGrouping();
     }
 }