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:
Portal and data services guideTo learn how to publish your own data as a hosted feature layer, visit Data hosting.
PrerequisitesBefore starting this tutorial:
You need an ArcGIS Location Platform or ArcGIS Online account.
Ensure your development environment meets the system requirements.
Optionally, you may want to install the ArcGIS Maps SDK for .NET to get access to project templates in Visual Studio (Windows only) and offline copies of the NuGet packages.
Develop or downloadYou have two options for completing this tutorial:
Option 1: Develop the codeTo start the tutorial, complete the Display a map tutorial. This creates a map to display the Santa Monica Mountains in California using the topographic basemap from the ArcGIS Basemap Styles service.
Open a Visual Studio solutionThe Visual Studio solution, project, and the namespace for all classes currently use the name DisplayAMap. You can rename these if you prefer them to reflect the current tutorial. Renaming is not required, your code will still work if you keep the original name.
The tutorial instructions and code use the name AddAFeatureLayer for the solution, project, and namespace. You can choose any name you like, but it should be the same for each of these.
Update the name for the solution and the project.
Rename the namespace used by classes in the project.
MapViewModel class, double-click the namespace name (DisplayAMap) to select it, and then right-click and choose Rename....Build the project.
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.
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.
The ArcGIS REST Services Directory 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.
In the Visual Studio > Solution Explorer, double-click MapViewModel.cs to open the file.
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.
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()
{
// Create a new map with a 'topographic vector' basemap.
Map map = new Map(BasemapStyle.ArcGISTopographic);
// Set the initial viewpoint around the Santa Monica Mountains in California.
var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
map.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
// Set the view model's Map property with the map.
Map = map;
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"
);
You will create three new FeatureLayer to display the hosted layer at each URI.
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);
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);
Click Debug > Start Debugging (or press <F5> on the keyboard) to run the app. If your app uses user authentication, enter your ArcGIS Online credentials when prompted.
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.
Alternatively, you can download the tutorial solution, as follows.
Option 2: Download the solutionClick the Download solution link in the right-hand panel of the page.
Unzip the file to a location on your machine.
Open the .sln file in Visual Studio.
Since the downloaded solution does not contain authentication credentials, you must first set up authentication to create credentials, and then add the developer credentials to the solution.
Set up authenticationTo access the secure ArcGIS location services used in this tutorial, you must implement API key authentication or user authentication using an ArcGIS Location Platform or an ArcGIS Online account.
You can implement API key authentication or user authentication in this tutorial. Compare the differences below:
API key authentication
Learn more in API key authentication.
User authentication
Learn more in User authentication.
Security and authentication guideTo learn more about the different types of authentication, visit Types of authentication.
Create a new API key access token with privileges to access the secure resources used in this tutorial.
Complete the Create an API key tutorial and create an API key with the following privilege(s):
Copy and paste the API key access token into a safe location. It will be used in a later step.
Create new OAuth credentials to access the secure resources used in this tutorial.
WarningConfiguration steps later in the tutorial will assume that your redirect URL is my-app://auth. If you use a different URL, make sure to configure your app's settings accordingly.
Complete the Create OAuth credentials for user authentication tutorial to obtain a Client ID and Redirect URL.
A Client ID uniquely identifies your app on the authenticating server. If the server cannot find an app with the provided Client ID, it will not proceed with authentication.
The Redirect URL (also referred to as a callback url) is used to identify a response from the authenticating server when the system returns control back to your app after an OAuth login. Since it does not necessarily represent a valid endpoint that a user could navigate to, the redirect URL can use a custom scheme, such as my-app://auth. It is important to make sure the redirect URL used in your app's code matches a redirect URL configured on the authenticating server.
Copy and paste the Client ID and Redirect URL into a safe location. They will be used in a later step.
All users that access this application need account privileges to access the ArcGIS Basemap Styles service.
Set developer credentials in the solutionTo allow your app users to access ArcGIS location services, use the developer credentials that you created in the Set up authentication step to authenticate requests for resources.
In Visual Studio, in the Solution Explorer, click App.xaml.cs to open the file.
Set the ArcGISEnvironment.ApiKey property with your API key access token.
App.xaml.cs
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protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
// Set the access token for ArcGIS Maps SDK for .NET.
Esri.ArcGISRuntime.ArcGISRuntimeEnvironment.ApiKey = "YOUR_ACCESS_TOKEN";
// Call a function to set up the AuthenticationManager for OAuth.
UserAuth.ArcGISLoginPrompt.SetChallengeHandler();
}
Remove the code that sets up user authentication.
App.xaml.cs
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protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
// Set the access token for ArcGIS Maps SDK for .NET.
Esri.ArcGISRuntime.ArcGISRuntimeEnvironment.ApiKey = "YOUR_ACCESS_TOKEN";
// Call a function to set up the AuthenticationManager for OAuth.
UserAuth.ArcGISLoginPrompt.SetChallengeHandler();
}
Best Practice: The access token is stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.
From the Visual Studio Solution explorer window, open the ArcGISLoginPrompt.cs file.
Set your values for the client ID (OAuthClientID) and the redirect URL (OAuthRedirectUrl). These are the user authentication settings you created in the Set up authentication step.
ArcGISLoginPrompt.cs
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internal static class ArcGISLoginPrompt
{
private const string ArcGISOnlineUrl = "https://www.arcgis.com/sharing/rest";
// Specify the Client ID and Redirect URL to use with OAuth authentication.
// See the instructions here for creating OAuth app settings:
// https://developers.arcgis.com/documentation/security-and-authentication/user-authentication/tutorials/create-oauth-credentials-user-auth/
private const string AppClientId = "YOUR_CLIENT_ID";
private const string OAuthRedirectUrl = "YOUR_REDIRECT_URL";
In Visual Studio, in the Solution Explorer, click App.xaml.cs to open the file.
Remove the line of code that sets an API key access token.
App.xaml.cs
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protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
// Set the access token for ArcGIS Maps SDK for .NET.
Esri.ArcGISRuntime.ArcGISRuntimeEnvironment.ApiKey = "YOUR_ACCESS_TOKEN";
// Call a function to set up the AuthenticationManager for OAuth.
UserAuth.ArcGISLoginPrompt.SetChallengeHandler();
}
Best Practice: The OAuth credentials are stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.
Run the solutionClick Debug > Start Debugging (or press <F5> on the keyboard) to run the app. If your app uses user authentication, enter your ArcGIS Online credentials when prompted.
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:
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