LayerCollection Class

public class LayerCollection : RuntimeObservableCollection<Layer>

// Copyright 2017 Esri.
// 
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using System;
using System.Linq;
using Android.App;
using Android.OS;
using Android.Widget;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Rasters;

namespace ArcGISRuntime.Samples.RasterLayerGeoPackage
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("68ec42517cdd439e81b036210483e8e7")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Raster layer (GeoPackage)",
        "Data",
        "This sample demonstrates how to open a GeoPackage and show a GeoPackage raster in a raster layer.",
        "The GeoPackage will be downloaded from an ArcGIS Online portal automatically.")]
    public class RasterLayerGeoPackage : Activity
    {
        private MapView _myMapView;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Raster layer (GeoPackage)";

            // Create the UI, setup the control references and execute initialization
            CreateLayout();
            Initialize();
        }

        private async void Initialize()
        {
            // Create a new map
            _myMapView.Map = new Map(Basemap.CreateLightGrayCanvas());

            // Get the full path
            string geoPackagePath = GetGeoPackagePath();

            try
            {
                // Open the GeoPackage
                GeoPackage myGeoPackage = await GeoPackage.OpenAsync(geoPackagePath);

                // Read the raster images and get the first one
                Raster gpkgRaster = myGeoPackage.GeoPackageRasters.FirstOrDefault();

                // Make sure an image was found in the package
                if (gpkgRaster == null) { return; }

                // Create a layer to show the raster
                RasterLayer newLayer = new RasterLayer(gpkgRaster);
                await newLayer.LoadAsync();

                // Set the viewpoint
                await _myMapView.SetViewpointAsync(new Viewpoint(newLayer.FullExtent));

                // Add the image as a raster layer to the map (with default symbology)
                _myMapView.Map.OperationalLayers.Add(newLayer);
            }
            catch (Exception e)
            {
                new AlertDialog.Builder(this).SetMessage(e.ToString()).SetTitle("Error").Show();
            }
        }

        private static string GetGeoPackagePath()
        {
            return DataManager.GetDataFolder("68ec42517cdd439e81b036210483e8e7", "AuroraCO.gpkg");
        }

        private void CreateLayout()
        {
            // Create a new vertical layout for the app
            LinearLayout layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Add a map view to the layout
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

            // Show the layout in the app
            SetContentView(layout);
        }
    }
}

// Copyright 2017 Esri.
// 
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using System;
using ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using System.Linq;
using Xamarin.Forms;

namespace ArcGISRuntime.Samples.RasterLayerGeoPackage
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Raster layer (GeoPackage)",
        "Data",
        "This sample demonstrates how to open a GeoPackage and show a GeoPackage raster in a raster layer.",
        "The GeoPackage will be downloaded from an ArcGIS Online portal automatically.")]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("68ec42517cdd439e81b036210483e8e7")]
    public partial class RasterLayerGeoPackage : ContentPage
    {
        public RasterLayerGeoPackage()
        {
            InitializeComponent();

            // Read data from the GeoPackage
            Initialize();
        }

        private async void Initialize()
        {
            // Create a new map
            MyMapView.Map = new Map(Basemap.CreateLightGrayCanvas());

            // Get the full path
            string geoPackagePath = GetGeoPackagePath();

            try
            {
                // Open the GeoPackage
                GeoPackage myGeoPackage = await GeoPackage.OpenAsync(geoPackagePath);

                // Read the raster images and get the first one
                Raster gpkgRaster = myGeoPackage.GeoPackageRasters.FirstOrDefault();

                // Make sure an image was found in the package
                if (gpkgRaster == null) { return; }

                // Create a layer to show the raster
                RasterLayer newLayer = new RasterLayer(gpkgRaster);
                await newLayer.LoadAsync();

                // Set the viewpoint
                await MyMapView.SetViewpointAsync(new Viewpoint(newLayer.FullExtent));

                // Add the image as a raster layer to the map (with default symbology)
                MyMapView.Map.OperationalLayers.Add(newLayer);
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private static string GetGeoPackagePath()

        {
            return DataManager.GetDataFolder("68ec42517cdd439e81b036210483e8e7", "AuroraCO.gpkg");
        }
    }
}

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"             
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms"
             xmlns:mapping="clr-namespace:Esri.ArcGISRuntime.Mapping;assembly=Esri.ArcGISRuntime" 
             x:Class="ArcGISRuntime.Samples.RasterLayerGeoPackage.RasterLayerGeoPackage">
    <esriUI:MapView x:Name="MyMapView"/>
</ContentPage>