private void FilterItem(string filter) { PatientsList.BeginRefresh(); if (string.IsNullOrEmpty(filter)) { PatientsList.ItemsSource = patientItems; } else { PatientsList.ItemsSource = patientItems.Where(p => p.FirstName.ToLower().Contains(filter.ToLower()) || p.LastName.ToLower().Contains(filter.ToLower())); } PatientsList.EndRefresh(); }