Feature collection layer from query result

FeatureCollectionLayer from query results
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// Copyright 2016 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 Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using UIKit;

namespace ArcGISRuntime.Samples.FeatureCollectionLayerFromQuery
{
    [Register("FeatureCollectionLayerFromQuery")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Feature collection layer from query result",
        "Layers",
        "This sample demonstrates how to create a feature collection layer to show a query result from a service feature table.",
        "")]
    public class FeatureCollectionLayerFromQuery : UIViewController
    {
        // Reference to the MapView used in the app
        private MapView _myMapView;

        // URL for a feature service layer to query
        private const string FeatureLayerUrl = "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Wildfire/FeatureServer/0";

        public FeatureCollectionLayerFromQuery()
        {
            Title = "Add a query result as a feature collection layer";
        }
        
        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            // Create the layout
            CreateLayout();

            // Initialize the app
            Initialize();
        }

        public override void ViewDidLayoutSubviews()
        {
            // Setup the visual frame for the MapView
            _myMapView.Frame = new CoreGraphics.CGRect(0, 0, View.Bounds.Width, View.Bounds.Height);

            base.ViewDidLayoutSubviews();
        }

        private void Initialize()
        {
            try
            {
                // Create a new map with the oceans basemap and add it to the map view
                Map myMap = new Map(Basemap.CreateOceans());
                _myMapView.Map = myMap;

                // Call a function that will create a new feature collection layer from a service query
                GetFeaturesFromQuery();
            }
            catch (Exception ex)
            {
                UIAlertView alert = new UIAlertView("Error", "Unable to create feature collection layer: " + ex.Message, null, "OK");
                alert.Show();
            }
        }

        private async void GetFeaturesFromQuery()
        {
            // Create a service feature table to get features from
            ServiceFeatureTable featTable = new ServiceFeatureTable(new Uri(FeatureLayerUrl));

            // Create a query to get all features in the table
            QueryParameters queryParams = new QueryParameters();
            queryParams.WhereClause = "1=1";

            // Query the table to get all features
            FeatureQueryResult featureResult = await featTable.QueryFeaturesAsync(queryParams);

            // Create a new feature collection table from the result features
            FeatureCollectionTable collectTable = new FeatureCollectionTable(featureResult);

            // Create a feature collection and add the table
            FeatureCollection featCollection = new FeatureCollection();
            featCollection.Tables.Add(collectTable);

            // Create a layer to display the feature collection, add it to the map's operational layers
            FeatureCollectionLayer featCollectionTable = new FeatureCollectionLayer(featCollection);
            _myMapView.Map.OperationalLayers.Add(featCollectionTable);
        }

        private void CreateLayout()
        {
            // Create a new MapView
            _myMapView = new MapView();

            // Add the MapView the page
            View.AddSubview(_myMapView);
        }
    }
}


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