public override void OnNavigatingTo(NavigationParameters parameters) { base.OnNavigatingTo(parameters); if (parameters.TryGetParam <string>(MainPage.AnotherParameter, out var paramString)) { Title = paramString; } if (!Contacts.Any()) { var contacts = _contactService.GetContacts(); foreach (var contact in contacts) { //TODO: opportunity to use enhanced observable collection from MVVM Helpers package? Contacts.Add(contact); } } }