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Reverse geocode

Estimated address for a geographic point


// Copyright 2019 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:
// 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 Android.App;
using Android.OS;
using Android.Widget;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks.Geocoding;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;
using Android.Views;

namespace ArcGISRuntimeXamarin.Samples.ReverseGeocode
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
        "Reverse geocode",
        "Use an online geocoding service to find the address for a point.",
    public class ReverseGeocode : Activity
        // Create and hold reference to the MapView.
        private readonly MapView _myMapView = new MapView();

        // Service Uri to be provided to the LocatorTask (geocoder).
        private readonly Uri _serviceUri = new Uri("");

        // The LocatorTask provides geocoding services.
        private LocatorTask _geocoder;

        protected override void OnCreate(Bundle bundle)

            Title = "Reverse geocode";


        private async void Initialize()
            // Create new Map with basemap.
            Map myMap = new Map(Basemap.CreateImageryWithLabels());

            // Provide used Map to the MapView.
            _myMapView.Map = myMap;

            // Add a graphics overlay to the map for showing where the user tapped.
            _myMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Enable tap-for-info pattern on results.
            _myMapView.GeoViewTapped += _myMapView_GeoViewTapped;

            // Initialize the LocatorTask with the provided service Uri.
                _geocoder = await LocatorTask.CreateAsync(_serviceUri);
            catch (Exception e)
                new AlertDialog.Builder(this).SetMessage(e.ToString()).SetTitle("Error").Show();

            // Set the initial viewpoint.
            await _myMapView.SetViewpointCenterAsync(34.058, -117.195, 5e4);

        private async void _myMapView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
                // Clear the existing graphics & callouts.

                // Add a graphic for the tapped point.
                Graphic pinGraphic = await GraphicForPoint(e.Location);

                // Normalize the geometry - needed if the user crosses the international date line.
                MapPoint normalizedPoint = (MapPoint)GeometryEngine.NormalizeCentralMeridian(e.Location);

                // Reverse geocode to get addresses.
                IReadOnlyList<GeocodeResult> addresses = await _geocoder.ReverseGeocodeAsync(normalizedPoint);

                // Get the first result.
                GeocodeResult address = addresses.First();

                // Use the city and region for the Callout Title.
                string calloutTitle = address.Attributes["Address"].ToString();

                // Use the metro area for the Callout Detail.
                string calloutDetail = address.Attributes["City"] +
                                       " " + address.Attributes["Region"] +
                                       " " + address.Attributes["CountryCode"];

                // Define the callout.
                CalloutDefinition calloutBody = new CalloutDefinition(calloutTitle, calloutDetail);

                // Show the callout on the map at the tapped location.
                _myMapView.ShowCalloutForGeoElement(pinGraphic, e.Position, calloutBody);
            catch (Exception ex)
                new AlertDialog.Builder(this).SetMessage("No results found.").SetTitle("No results").Show();

        private async Task<Graphic> GraphicForPoint(MapPoint point)
            // Get current assembly that contains the image.
            Assembly currentAssembly = Assembly.GetExecutingAssembly();

            // Get image as a stream from the resources.
            // Picture is defined as EmbeddedResource and DoNotCopy.
            Stream resourceStream = currentAssembly.GetManifestResourceStream(

            // Create new symbol using asynchronous factory method from stream.
            PictureMarkerSymbol pinSymbol = await PictureMarkerSymbol.CreateAsync(resourceStream);
            pinSymbol.Width = 60;
            pinSymbol.Height = 60;
            // The image is a pin; offset the image so that the pinpoint.
            //     is on the point rather than the image's true center.
            pinSymbol.LeaderOffsetX = 30;
            pinSymbol.OffsetY = 14;
            return new Graphic(point, pinSymbol);

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

            // Add a help label.
            TextView helpLabel = new TextView(this);
            helpLabel.Text = "Tap to find the nearest address.";
            helpLabel.Gravity = GravityFlags.Center;

            // Add the map view to the layout.

            // Show the layout in the app.

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