Offline geocode

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Geocode addresses to locations and reverse geocode locations to addresses offline.
Image of offline geocode
Use case

You can use an address locator file to geocode addresses and locations. For example, you could provide offline geocoding capabilities to field workers repairing critical infrastructure in a disaster when network availability is limited.
How to use the sample

Type the address in the Search menu option or select from the list to Geocode the address and view the result on the map. Tap the location you want to reverse geocode. Tap the pin to see the full address.
How it works

Use the path of a .loc file to create a LocatorTask object.
Set up GeocodeParameters and call GeocodeAsync to get geocode results.
Relevant API

GeocodeParameters
GeocodeResult
LocatorTask
ReverseGeocodeParameters
Offline data

This sample downloads the following items from ArcGIS Online automatically:
San Diego Streets Tile Package - Streets Tile Package (tpkx) for the City of San Diego.
San Diego Offline Locator - Includes San Diego Locator Offline Dataset.
Sample Code

OfflineGeocode.cs
Use dark colors for code blocksCopy
﻿// 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: 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 ArcGISRuntime;
using ArcGISRuntime.Samples.Managers;
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 Foundation;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;
using UIKit;

namespace ArcGISRuntimeXamarin.Samples.OfflineGeocode
{
    [Register("OfflineGeocode")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Offline geocode",
        category: "Search",
        description: "Geocode addresses to locations and reverse geocode locations to addresses offline.",
        instructions: "Type the address in the Search menu option or select from the list to `Geocode` the address and view the result on the map. Tap the location you want to reverse geocode. Tap the pin to see the full address.",
        tags: new[] { "geocode", "geocoder", "locator", "offline", "package", "query", "search" })]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("22c3083d4fa74e3e9b25adfc9f8c0496", "3424d442ebe54f3cbf34462382d3aebe")]
    public class OfflineGeocode : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;
        private UISearchBar _addressSearchBar;

        // Addresses for suggestion.
        private readonly string[] _addresses =
        {
            "910 N Harbor Dr, San Diego, CA 92101",
            "2920 Zoo Dr, San Diego, CA 92101",
            "111 W Harbor Dr, San Diego, CA 92101",
            "868 4th Ave, San Diego, CA 92101",
            "750 A St, San Diego, CA 92101"
        };

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

        public OfflineGeocode()
        {
            Title = "Offline geocode";
        }

        private async void Initialize()
        {
            // Get the offline tile package and use it as a basemap.
            string basemapPath = DataManager.GetDataFolder("22c3083d4fa74e3e9b25adfc9f8c0496", "streetmap_SD.tpkx");
            ArcGISTiledLayer tiledBasemapLayer = new ArcGISTiledLayer(new TileCache(basemapPath));

            // Create new Map with basemap.
            Map myMap = new Map(new Basemap(tiledBasemapLayer));

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

            // Add a graphics overlay for showing pins.
            _myMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            try
            {
                // Get the path to the locator.
                string locatorPath = DataManager.GetDataFolder("3424d442ebe54f3cbf34462382d3aebe", "SanDiego_StreetAddress.loc");

                // Load the geocoder.
                _geocoder = await LocatorTask.CreateAsync(new Uri(locatorPath));

                // Enable controls now that the geocoder is ready.
                _addressSearchBar.UserInteractionEnabled = true;
            }
            catch (Exception e)
            {
                new UIAlertView("Error", e.ToString(), (IUIAlertViewDelegate) null, "OK", null).Show();
            }
        }

        private async void UpdateSearch()
        {
            // Get the text in the search bar.
            string enteredText = _addressSearchBar.Text;

            // Clear existing marker.
            _myMapView.GraphicsOverlays[0].Graphics.Clear();
            _myMapView.DismissCallout();

            // Return if the textbox is empty or the geocoder isn't ready.
            if (String.IsNullOrWhiteSpace(enteredText) || _geocoder == null)
            {
                return;
            }

            try
            {
                // Get suggestions based on the input text.
                IReadOnlyList<GeocodeResult> geocodeResults = await _geocoder.GeocodeAsync(enteredText);

                // Stop if there are no suggestions.
                if (!geocodeResults.Any())
                {
                    new UIAlertView("No results", "No results found.", (IUIAlertViewDelegate) null, "OK", null).Show();
                    return;
                }

                // Get the full address for the first suggestion.
                GeocodeResult firstSuggestion = geocodeResults.First();
                IReadOnlyList<GeocodeResult> addresses = await _geocoder.GeocodeAsync(firstSuggestion.Label);

                // Stop if the geocoder does not return a result.
                if (addresses.Count < 1)
                {
                    return;
                }

                // Show a graphic for the address.
                Graphic point = await GraphicForPoint(addresses.First().DisplayLocation);
                _myMapView.GraphicsOverlays[0].Graphics.Add(point);

                // Update the map extent to show the marker.
                _myMapView.SetViewpoint(new Viewpoint(addresses.First().Extent));
            }
            catch (Exception e)
            {
                new UIAlertView("Error", e.ToString(), (IUIAlertViewDelegate) null, "OK", null).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(
                "ArcGISRuntime.Resources.PictureMarkerSymbols.pin_star_blue.png");

            // 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 AddressSearch_ListButtonClicked(object sender, EventArgs e)
        {
            // Create the alert view.
            UIAlertController alert = UIAlertController.Create("Suggestions", "Location searches to try", UIAlertControllerStyle.Alert);

            // Populate the view with one action per address suggestion.
            foreach (string address in _addresses)
            {
                alert.AddAction(UIAlertAction.Create(address, UIAlertActionStyle.Default, obj =>
                {
                    _addressSearchBar.Text = address;
                    UpdateSearch();
                }));
            }

            // Show the alert view.
            PresentViewController(alert, true, null);
        }

        private async void MyMapView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Clear existing callout and graphics.
                _myMapView.DismissCallout();
                _myMapView.GraphicsOverlays[0].Graphics.Clear();

                // Add a graphic for the tapped point.
                Graphic pinGraphic = await GraphicForPoint(e.Location);
                _myMapView.GraphicsOverlays[0].Graphics.Add(pinGraphic);

                // Reverse geocode to get addresses.
                ReverseGeocodeParameters parameters = new ReverseGeocodeParameters();
                parameters.ResultAttributeNames.Add("*");
                parameters.MaxResults = 1;
                IReadOnlyList<GeocodeResult> addresses = await _geocoder.ReverseGeocodeAsync(e.Location, parameters);

                // Skip if there are no results.
                if (!addresses.Any())
                {
                    new UIAlertView("No results", "No results found.", (IUIAlertViewDelegate) null, "OK", null).Show();
                    return;
                }

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

                // Use the address as the callout title.
                string calloutTitle = address.Attributes["StAddr"].ToString();
                string calloutDetail = address.Attributes["City"].ToString() + ", " + address.Attributes["RegionAbbr"] + " " + address.Attributes["Postal"];

                // 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 UIAlertView("Error", ex.ToString(), (IUIAlertViewDelegate) null, "OK", null).Show();
            }
        }

        private void AddressSearchBar_Clicked(object sender, EventArgs e)
        {
            UpdateSearch();

            // Dismiss the keyboard.
            _addressSearchBar.ResignFirstResponder();
        }

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();
            Initialize();
        }

        public override void LoadView()
        {
            // Create the views.
            View = new UIView {BackgroundColor = ApplicationTheme.BackgroundColor};

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            _addressSearchBar = new UISearchBar();
            _addressSearchBar.TranslatesAutoresizingMaskIntoConstraints = false;
            _addressSearchBar.UserInteractionEnabled = false;
            _addressSearchBar.ShowsSearchResultsButton = true;

            // Add the views.
            View.AddSubviews(_myMapView, _addressSearchBar);

            // Lay out the views.
            NSLayoutConstraint.ActivateConstraints(new[]
            {
                _addressSearchBar.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _addressSearchBar.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _addressSearchBar.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),

                _myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _myMapView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor),
                _myMapView.TopAnchor.ConstraintEqualTo(_addressSearchBar.BottomAnchor)
            });
        }

        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            // Subscribe to events.
            _myMapView.GeoViewTapped += MyMapView_GeoViewTapped;
            _addressSearchBar.ListButtonClicked += AddressSearch_ListButtonClicked;
            _addressSearchBar.SearchButtonClicked += AddressSearchBar_Clicked;
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            // Unsubscribe from events, per best practice.
            _myMapView.GeoViewTapped -= MyMapView_GeoViewTapped;
            _addressSearchBar.ListButtonClicked -= AddressSearch_ListButtonClicked;
            _addressSearchBar.SearchButtonClicked -= AddressSearchBar_Clicked;
        }
    }
}