private void OnSave()
        {
            var database = new Database();
            database.AddContact(_contact);

            _navigation.GoBack();
        }
 public MainViewModel(INavigation navigation)
 {
     _navigation = navigation;
     _database = new Database();
     Contacts = new ObservableCollection<Contact>(_database.SearchContacts(""));
     AddCommand = new Command(ShowAddWindow);
 }