Add features

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// 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 Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using UIKit;

namespace ArcGISRuntimeXamarin.Samples.AddFeatures
{
    [Register("AddFeatures")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Add features",
        category: "Data",
        description: "Add features to a feature layer.",
        instructions: "Tap on a location on the map to add a feature at that location.",
        tags: new[] { "edit", "feature", "online service" })]
    public class AddFeatures : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;

        // URL to the feature service.
        private const string FeatureServiceUrl = "https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/0";

        // Hold a reference to the feature table.
        private ServiceFeatureTable _damageFeatureTable;

        public AddFeatures()
        {
            Title = "Add features (feature service)";
        }

        private void Initialize()
        {
            // Create the map with streets basemap.
            _myMapView.Map = new Map(BasemapStyle.ArcGISStreets);

            // Create the feature table, referring to the Damage Assessment feature service.
            _damageFeatureTable = new ServiceFeatureTable(new Uri(FeatureServiceUrl));

            // Create a feature layer to visualize the features in the table.
            FeatureLayer damageLayer = new FeatureLayer(_damageFeatureTable);

            // Add the layer to the map.
            _myMapView.Map.OperationalLayers.Add(damageLayer);

            // Zoom to the United States.
            _myMapView.SetViewpointCenterAsync(new MapPoint(-10800000, 4500000, SpatialReferences.WebMercator), 3e7);
        }

        private async void MapView_Tapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Create the feature.
                ArcGISFeature feature = (ArcGISFeature) _damageFeatureTable.CreateFeature();

                // Get the normalized geometry for the tapped location and use it as the feature's geometry.
                MapPoint tappedPoint = (MapPoint) GeometryEngine.NormalizeCentralMeridian(e.Location);
                feature.Geometry = tappedPoint;

                // Set feature attributes.
                feature.SetAttributeValue("typdamage", "Minor");
                feature.SetAttributeValue("primcause", "Earthquake");

                // Add the feature to the table.
                await _damageFeatureTable.AddFeatureAsync(feature);

                // Apply the edits to the service.
                await _damageFeatureTable.ApplyEditsAsync();

                // Update the feature to get the updated objectid - a temporary ID is used before the feature is added.
                feature.Refresh();

                // Confirm feature addition.
                ShowMessage($"Created feature {feature.Attributes["objectid"]}", "Success!");
            }
            catch (Exception ex)
            {
                ShowMessage(ex.ToString(), "Error adding feature");
            }
        }

        private void ShowMessage(string message, string title)
        {
            // Create the alert controller.
            UIAlertController alertController = UIAlertController.Create(title, message, UIAlertControllerStyle.Alert);
            alertController.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));

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

        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;

            UILabel helpLabel = new UILabel
            {
                Text = "Tap to add features.",
                AdjustsFontSizeToFitWidth = true,
                TextAlignment = UITextAlignment.Center,
                BackgroundColor = UIColor.FromWhiteAlpha(0, .6f),
                TextColor = UIColor.White,
                Lines = 1,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

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

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

                helpLabel.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                helpLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                helpLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                helpLabel.HeightAnchor.ConstraintEqualTo(40)
            });
        }

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

            // Subscribe to events.
            _myMapView.GeoViewTapped += MapView_Tapped;
        }

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

            // Unsubscribe from events, per best practice.
            _myMapView.GeoViewTapped -= MapView_Tapped;
        }
    }
}