Add a feature layer

Learn how to use a URL to access and display a feature layer in a map.

A map contains layers of geographic data. A map contains a basemap layer and, optionally, one or more data layers. This tutorial shows you how to access and display a feature layer in a map. You access feature layers with an item ID or URL. You will use URLs to access the Trailheads, Trails, and Parks and Open Spaces feature layers and display them in a map.

A feature layer is a dataset in a feature service hosted in ArcGIS. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. You can use feature layers to store, access, and manage large amounts of geographic data for your applications.

In this tutorial, you use URLs to access and display three different feature layers hosted in ArcGIS Online:

• Trailheads (points)
• Trails (lines)
• Parks and Open Spaces (polygons)

Prerequisites

Steps

Open a Visual Studio solution

1. To start the tutorial, complete the Display a map tutorial or download and unzip the solution.

2. Open the .sln file in Visual Studio.

3. If you downloaded the solution project, set your API key.

   Instructions for setting the API key

   An API Key enables access to services, web maps, and web scenes hosted in ArcGIS Online.

   If necessary, set the  API Key.

   1. Go to your developer dashboard to get your API key. For these tutorials, use your default API key. It is scoped to include all of the services demonstrated in the tutorials.

   2. In Visual Studio, in the Solution Explorer, click App.xaml.cs.

   3. In the App class, add an override for the OnStartup() function to set the ApiKey property on ArcGISRuntimeEnvironment.

      App.xaml.cs

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          public partial class App : Application
          {
      
              protected override void OnStartup(StartupEventArgs e)
              {
                  base.OnStartup(e);
                  // Note: it is not best practice to store API keys in source code.
                  // The API key is referenced here for the convenience of this tutorial.
                  Esri.ArcGISRuntime.ArcGISRuntimeEnvironment.ApiKey = "YOUR_API_KEY";
              }
      
          }
      }

Update the tutorial name used in the project (optional)

The Visual Studio solution, project, and the namespace for all classes currently use the name DisplayAMap. Follow the steps below if you prefer the name to reflect the current tutorial. This is not required, your code will still work if you keep the original name. The instructions will refer to AddAFeatureLayer rather than DisplayAMap.

1. Update the name for the solution and the project.

   • In the Visual Studio > Solution Explorer, right-click the solution name and choose Rename. Name the solution AddAFeatureLayer.
   • In the Solution Explorer, right-click the project name and choose Rename. Name the project AddAFeatureLayer.

2. Update the name of the namespace used by classes in the project.

   • In the Solution Explorer, expand the project node.
   • Double-click MapViewModel.cs in the Solution Explorer to open the file.
   • In the MapViewModel class, double-click the namespace name (DisplayAMap) to highlight it, right-click and choose Rename....
   • Rename the namespace AddAFeatureLayer.
   • Click Apply in the Rename: DisplayAMap window that appears in the upper-right of the code window. This will rename the namespace throughout your project.

3. Build the project.

   • Choose Build > Build solution (or press <F6>).

Create URIs to reference feature service data

To display three new data layers (also known as operational layers) on top of the current basemap, you will create FeatureLayers using URIs to reference datasets hosted in ArcGIS Online.

1. Open a browser and navigate to the URL for Parks and Open Spaces to view metadata about the layer. To display the layer in your app, you only need the URL.

   More info

   The service page provides information such as the geometry type, the geographic extent, the minimum and maximum scale at which features are visible, and the attributes (fields) it contains. You can preview the layer by clicking on ArcGIS.com Map in the "View In:" list at the top of the page.

2. In the Visual Studio > Solution Explorer, double-click MapViewModel.cs to open the file.

   More info

   The project uses the Model-View-ViewModel (MVVM) design pattern to separate the application logic (view model) from the user interface (view). MapViewModel.cs contains the view model class for the application, called MapViewModel. See the Microsoft documentation for more information about the Model-View-ViewModel pattern.

3. In the SetupMap() function, add code that defines the URIs to the hosted layers. You will add: Trailheads (points), Trails (lines), and Parks and Open Spaces (polygons).

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           private void SetupMap()
           {
               Map = new Map(BasemapStyle.ArcGISTopographic);
   
               var parksUri = new Uri(
                   "https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Parks_and_Open_Space/FeatureServer/0"
                   );
   
               var trailsUri = new Uri(
                   "https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Trails/FeatureServer/0"
                   );
   
               var trailheadsUri = new Uri(
                   "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
                   );
   

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Create feature layers to display the hosted data

You will create three new FeatureLayer to display the hosted layer at each URI.

1. In the SetupMap() function, create new feature layers and pass the appropriate URI to the constructor for each.

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               var trailheadsUri = new Uri(
                   "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
                   );
   
               var parksLayer = new FeatureLayer(parksUri);
               var trailsLayer = new FeatureLayer(trailsUri);
               var trailheadsLayer = new FeatureLayer(trailheadsUri);
   

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2. Add the feature layers to the map. Data layers are displayed in the order in which they are added. Polygon layers should be added before layers with lines or points if there's a chance the polygon symbols will obscure features beneath.

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               var parksLayer = new FeatureLayer(parksUri);
               var trailsLayer = new FeatureLayer(trailsUri);
               var trailheadsLayer = new FeatureLayer(trailheadsUri);
   
               Map.OperationalLayers.Add(parksLayer);
               Map.OperationalLayers.Add(trailsLayer);
               Map.OperationalLayers.Add(trailheadsLayer);
   

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3. Click Debug > Start Debugging (or press <F5> on the keyboard) to run the app.

You should see point, line, and polygon features (representing trailheads, trails, and parks) draw on the map for an area in the Santa Monica Mountains.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials:

• Add a point, line, and polygon
• Display a web map
• Display a scene
• Search for an address