public MainPage() { MapControl.Map?.Layers.Add(OpenStreetMap.CreateTileLayer()); Content = new Grid { ColumnDefinitions = { new ColumnDefinition { Width = new GridLength(1, GridUnitType.Auto) }, new ColumnDefinition { Width = new GridLength(2, GridUnitType.Star) } }, Children = { new VerticalStackLayout() { Spacing = 20, Children = { SampleCategoryPicker, SampleList } }.Column(0).Padding(20), MapControl.Column(1) } }; SampleList.ItemSelected += SampleList_ItemSelected; allSamples = AllSamples.GetSamples() ?? new List <ISampleBase>(); var categories = allSamples.Select(s => s.Category).Distinct().OrderBy(c => c); SampleCategoryPicker !.ItemsSource = categories.ToList <string>(); SampleCategoryPicker.SelectedIndexChanged += SampleCategoryPicker_SelectedIndexChanged;; SampleCategoryPicker.SelectedItem = "Info"; }