Unique value renderer

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

namespace ArcGISRuntime.Samples.RenderUniqueValues
{
    [Register("RenderUniqueValues")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Unique value renderer",
        category: "Symbology",
        description: "Render features in a layer using a distinct symbol for each unique attribute value.",
        instructions: "The map with the symbolized feature layer will be shown automatically when the sample loads.",
        tags: new[] { "draw", "renderer", "symbol", "symbology", "values" })]
    public class RenderUniqueValues : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;

        public RenderUniqueValues()
        {
            Title = "Render unique values";
        }

        private void Initialize()
        {
            // Create new Map with a topographic basemap.
            Map myMap = new Map(BasemapStyle.ArcGISTopographic);

            // Create URI pointing to the feature service.
            Uri serviceUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3");

            // Create service feature table.
            ServiceFeatureTable statesFeatureTable = new ServiceFeatureTable(serviceUri);

            // Create a new feature layer using the service feature table.
            FeatureLayer statesLayer = new FeatureLayer(statesFeatureTable);

            // Create a new unique value renderer.
            UniqueValueRenderer regionRenderer = new UniqueValueRenderer();

            // Add the "SUB_REGION" field to the renderer.
            regionRenderer.FieldNames.Add("SUB_REGION");

            // Define a line symbol to use for the region fill symbols.
            SimpleLineSymbol stateOutlineSymbol = new SimpleLineSymbol(
                SimpleLineSymbolStyle.Solid, System.Drawing.Color.White, 0.7);

            // Define distinct fill symbols for a few regions (use the same outline symbol).
            SimpleFillSymbol pacificFillSymbol = new SimpleFillSymbol(
                SimpleFillSymbolStyle.Solid, System.Drawing.Color.Blue, stateOutlineSymbol);
            SimpleFillSymbol mountainFillSymbol = new SimpleFillSymbol(
                SimpleFillSymbolStyle.Solid, System.Drawing.Color.LawnGreen, stateOutlineSymbol);
            SimpleFillSymbol westSouthCentralFillSymbol = new SimpleFillSymbol(
                SimpleFillSymbolStyle.Solid, System.Drawing.Color.SandyBrown, stateOutlineSymbol);

            // Add values to the renderer: define the label, description, symbol, and attribute value for each.
            regionRenderer.UniqueValues.Add(
                new UniqueValue("Pacific", "Pacific Region", pacificFillSymbol, "Pacific"));
            regionRenderer.UniqueValues.Add(
                new UniqueValue("Mountain", "Rocky Mountain Region", mountainFillSymbol, "Mountain"));
            regionRenderer.UniqueValues.Add(
                new UniqueValue("West South Central", "West South Central Region", westSouthCentralFillSymbol, "West South Central"));

            // Set the default region fill symbol (transparent with no outline) for regions not explicitly defined in the renderer
            regionRenderer.DefaultSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Cross, System.Drawing.Color.Gray, null);
            regionRenderer.DefaultLabel = "Other";

            // Apply the unique value renderer to the states layer.
            statesLayer.Renderer = regionRenderer;

            // Add created layer to the map.
            myMap.OperationalLayers.Add(statesLayer);

            // Assign the map to the MapView.
            _myMapView.Map = myMap;

            // Feature table initialization.
            statesFeatureTable.RetryLoadAsync();
        }

        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;

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

            // 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)
            });
        }
    }
}