Access services with OAuth credentials (.NET MAUI)

Learn how to implement user authentication to access a secure ArcGIS service with OAuth credentials in a cross-platform app.

You can use different types of authentication to access secured ArcGIS services. To implement OAuth credentials for user authentication, you can use your ArcGIS account to register an app with your portal and get a Client ID, and then configure your app to redirect users to login with their credentials when the service or content is accessed. This is known as user authentication. If the app uses premium ArcGIS Online services that consume credits, for example, the app user's account will be charged.

In this tutorial, you will build an app that implements user authentication using OAuth credentials so users can sign in and be authenticated through ArcGIS Online to access the ArcGIS World Traffic service.

Prerequisites

Steps

Create OAuth credentials

OAuth credentials are required to implement user authentication. These credentials are created as an Application item in your organization's portal.

Open a Visual Studio solution

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

2. Open the .sln file in Visual Studio.

3. Open the MauiProgram.cs file and delete the code that sets your access token. Since your app uses OAuth, you will not need an access token.

   MauiProgram.cs

   Expand

   Use dark colors for code blocks

   20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

   Remove line

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   public static class MauiProgram
   {
       public static MauiApp CreateMauiApp()
   	{
   		var builder = MauiApp.CreateBuilder();
   		builder
   			.UseMauiApp<App>()
   			.ConfigureFonts(fonts =>
   			{
   				fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
   				fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
               });
   
   		builder.UseArcGISRuntime(config => config.UseApiKey("YOUR_ACCESS_TOKEN"));
   
   #if DEBUG
           builder.Logging.AddDebug();
   #endif
   
   		return builder.Build();
   	}
   }

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. These steps are not required, your code will still work if you keep the original name.

Add a reference to WinUIEx

1. In the Visual Studio > Solution Explorer, right-click the project node and choose Edit project file.

2. Include the following package reference in the AccessServicesWithOAuth.csproj file.

   AccessServicesWithOAuth.csproj

   Expand

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   	<!-- WinUIEx is used to workaround the lack of a WebAuthenticationBroker for WinUI. https://github.com/microsoft/WindowsAppSDK/issues/441 -->
   
   	<ItemGroup Condition="'$(TargetFramework)' == 'net8.0-windows10.0.19041.0'">
     		<PackageReference Include="WinUIEx" Version="2.3.4" />
   	</ItemGroup>
   

   Expand

3. Save and close the project file.

Platform-specific setup for WebAuthenticator functionality

The .NET MAUI WebAuthenticator helps you implement browser-based authentication flows, which listen for a callback to a specific URL registered to the app. To use the .NET MAUI WebAuthenticator some platform-specific setup is required.

Windows

For WinUI 3, the callback URI protocol needs to be included in the Package.appxmanifest file. The Protocol Name must match the URI scheme of the redirect URL on your ArcGIS Location Platform account.

1. In the Visual Studio > Solution Explorer, navigate to the Platforms\Windows folder.

2. Open the Package.appxmanifest file in an XML (text) editor and add the following lines.

   Package.appxmanifest

   Expand

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
     <Applications>
       <Application Id="App" Executable="$targetnametoken$.exe" EntryPoint="$targetentrypoint$">
         <uap:VisualElements
           DisplayName="$placeholder$"
           Description="$placeholder$"
           Square150x150Logo="$placeholder$.png"
           Square44x44Logo="$placeholder$.png"
           BackgroundColor="transparent">
           <uap:DefaultTile Square71x71Logo="$placeholder$.png" Wide310x150Logo="$placeholder$.png" Square310x310Logo="$placeholder$.png" />
           <uap:SplashScreen Image="$placeholder$.png" />
         </uap:VisualElements>
   
         <Extensions>
           <uap:Extension Category="windows.protocol">
             <uap:Protocol Name="my-app"/>
           </uap:Extension>
         </Extensions>
   
       </Application>
     </Applications>
   

   Expand

iOS and Mac Catalyst

The iOS and Mac Catalyst platforms require the inclusion of your app's callback URI pattern in their Info.plist files. The CFBundleURLSchemes value must match the URI scheme of the redirect URL on your ArcGIS Location Platform account.

1. In the Visual Studio > Solution Explorer, navigate to the Platforms\iOS folder.

2. Open the Info.plist file in an XML (text) editor and add the following lines. Make the same edits in the Platforms\MacCatalyst\Info.plist file.

   Info.plist

   Expand

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   	<key>XSAppIconAssets</key>
   	<string>Assets.xcassets/appicon.appiconset</string>
   
      <key>CFBundleURLTypes</key>
      <array>
         <dict>
            <key>CFBundleURLName</key>
            <string>My App</string>
            <key>CFBundleURLSchemes</key>
            <array>
                  <string>my-app</string>
            </array>
            <key>CFBundleTypeRole</key>
            <string>Editor</string>
         </dict>
      </array>
   

   Expand

Android

For Android, the AndroidManifest.xml file must be updated to include the CustomTabsService, which is required by the WebAuthenticator.

1. In the Visual Studio > Solution Explorer, navigate to the Platforms\Android folder.

2. Open the AndroidManifest.xml file in an XML (text) editor and add the following lines.

   AndroidManifest.xml

   Expand

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   	<!--https://github.com/dotnet/maui/issues/3760#issuecomment-1046241094-->
   
   	<queries>
   		<intent>
   			<action android:name="android.support.customtabs.action.CustomTabsService" />
   		</intent>
   	</queries>
   

   Expand

   Android also requires the implementation of WebAuthenticatorCallbackActivity class. This is included in the AuthenticationHelper.cs class covered in more detail later in this tutorial.

   More info

   Use dark colors for code blocksCopy

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
   100
   101
   102
   103
   104
   105
   106
   107
   108
   109
   110
   111
   112
   113
   114
   115
   116
   117
   118
   119
   120
   121
   122
   123
   124
   125
   126
   127
   128
   129
   130
   131
   132
   133
   134
   135
   136
   137
   138
   139
   140
   141
   142
   143
   144
   145
   146
   147
   148
   149
   150
   151
   152
   153
   154
   155
   156
   157
   158
   159
   160
   161
   162
   163
   164
   165
   166
   167
               [Activity(NoHistory = true, Exported = true, LaunchMode = LaunchMode.SingleTop)]
               [IntentFilter(new[] { Intent.ActionView },
                  Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
                  DataScheme = "my-app", DataHost = "auth")]
               public class WebAuthenticationCallbackActivity : WebAuthenticatorCallbackActivity
               {
               }
   

   The Microsoft documentation covers getting started with the .NET MAUI WebAuthenticator in more detail.

Add a traffic layer

You will add a layer to display the ArcGIS World Traffic service, a dynamic map service that presents historical and near real-time traffic information for different regions in the world. This is a secure service and requires an ArcGIS Online organizational subscription.

1. 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.

2. In the SetupMap() function, update the line that sets the Map property for the view model to instead store the map in a variable. Also change the line that sets the map's initial extent to use the variable.

   MapViewModel.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private void SetupMap()
           {
   
               // Create a new map with a 'topographic vector' basemap.
               var trafficMap = new Map(BasemapStyle.ArcGISTopographic);
   
               var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
   
               trafficMap.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
   
           }
   

3. Create an ArcGISMapImageLayer to display the traffic service and add it to the map's collection of data layers (operational layers).

   MapViewModel.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private void SetupMap()
           {
   
               // Create a new map with a 'topographic vector' basemap.
               var trafficMap = new Map(BasemapStyle.ArcGISTopographic);
   
               var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
   
               trafficMap.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
   
               // Create a layer to display the ArcGIS World Traffic service.
               var trafficServiceUrl = "https://traffic.arcgis.com/arcgis/rest/services/World/Traffic/MapServer";
               var trafficLayer = new ArcGISMapImageLayer(new Uri(trafficServiceUrl));
   
               // Add the traffic layer to the map's data layer collection.
               trafficMap.OperationalLayers.Add(trafficLayer);
   
           }
   

4. Set the view model's Map property. Data binding handles displaying the map in the view.

   MapViewModel.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private void SetupMap()
           {
   
               // Create a new map with a 'topographic vector' basemap.
               var trafficMap = new Map(BasemapStyle.ArcGISTopographic);
   
               var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
   
               trafficMap.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
   
               // Create a layer to display the ArcGIS World Traffic service.
               var trafficServiceUrl = "https://traffic.arcgis.com/arcgis/rest/services/World/Traffic/MapServer";
               var trafficLayer = new ArcGISMapImageLayer(new Uri(trafficServiceUrl));
   
               // Add the traffic layer to the map's data layer collection.
               trafficMap.OperationalLayers.Add(trafficLayer);
   
               // Set the view model Map property with the new map.
               this.Map = trafficMap;
   
           }
   

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

   More info

   If creating apps for Android or iOS, you will need the appropriate emulator, simulator, or device configured for testing (see System requirements for details)

You should see a map with the topographic basemap layer centered on the Santa Monica Mountains in California. The traffic layer doesn't appear because it requires authentication with ArcGIS Online.

Handle layer load errors

If a map attempts to load a layer based on a secured service without the required authentication, the layer is not added to the map. No exception is raised and unless you handle it in your code, the user may never know that the secured resource is missing from the map.

You will handle load status change events for the traffic layer and report an error message if the layer fails to load.

1. In the SetupMap() function, after the line that creates the traffic layer, add the following line of code to handle the layer's load status changed event. You will create the code for this handler in another step.

   MapViewModel.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private void SetupMap()
           {
   
               // Create a new map with a 'topographic vector' basemap.
               var trafficMap = new Map(BasemapStyle.ArcGISTopographic);
   
               var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
   
               trafficMap.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
   
               // Create a layer to display the ArcGIS World Traffic service.
               var trafficServiceUrl = "https://traffic.arcgis.com/arcgis/rest/services/World/Traffic/MapServer";
               var trafficLayer = new ArcGISMapImageLayer(new Uri(trafficServiceUrl));
   
               // Handle changes in the traffic layer's load status to check for errors.
               trafficLayer.LoadStatusChanged += TrafficLayer_LoadStatusChanged;
   
               // Add the traffic layer to the map's data layer collection.
               trafficMap.OperationalLayers.Add(trafficLayer);
   
               // Set the view model Map property with the new map.
               this.Map = trafficMap;
   
           }
   

2. Below the SetupMap() function, create the function that handles load status change events for the layer. If the layer fails to load, display an error message to the user.

   MapViewModel.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private async void TrafficLayer_LoadStatusChanged(object sender, Esri.ArcGISRuntime.LoadStatusEventArgs e)
   
           {
               // Report the error message if the traffic layer fails to load.
               if (e.Status == Esri.ArcGISRuntime.LoadStatus.FailedToLoad)
               {
                   var trafficLayer = sender as ArcGISMapImageLayer;
                   await MainThread.InvokeOnMainThreadAsync(() =>
                   {
                       Application.Current.MainPage.DisplayAlert("Traffic layer did not load", trafficLayer?.LoadError?.Message, "Ok");
                   });
               }
           }
   

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

   More info

   If creating apps for Android or iOS, you will need the appropriate emulator, simulator, or device configured for testing (see System requirements for details)

You should see the same map display, but this time a message box reports a "Token required" error when the traffic layer fails to load. An access token is an authorization string that provides secure access to content, data, and functionality in ArcGIS location services. To load the traffic service layer, you will use OAuth to get an access token based on ArcGIS Online credentials.

Implement user authentication using OAuth credentials

This API abstracts some of the details for user authentication using OAuth credentials in your app. You can use classes such as AuthenticationManager to request, store, and manage credentials for secure resources.

You will add an authentication helper class that uses AuthenticationManager and encapsulates additional authentication logic.

1. From the Visual Studio Project menu, choose Add class .... Name the class AuthenticationHelper.cs then click Add. The new class is added to your project and opens in Visual Studio.

2. Select all the code in the class and delete it.

3. Copy all of the code below and paste it into the AuthenticationHelper.cs class in your project.

   AuthenticationHelper.cs

   Use dark colors for code blocksCopy

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
   100
   101
   102
   103
   104
   105
   106
   107
   108
   109
   110
   111
   112
   113
   114
   115
   116
   117
   118
   119
   120
   121
   122
   123
   124
   125
   126
   127
   128
   129
   130
   131
   132
   133
   134
   135
   136
   137
   138
   139
   140
   141
   142
   143
   144
   145
   146
   147
   148
   149
   150
   151
   152
   153
   154
   155
   156
   157
   158
   159
   160
   161
   162
   163
   164
   165
   166
   167
   //   Copyright 2023 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
   //
   //   https://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.
   
   #if ANDROID
   
   using Android.App;
   using Application = Microsoft.Maui.Controls.Application;
   using Android.Content;
   using Android.Content.PM;
   
   #endif
   
   using Esri.ArcGISRuntime.Security;
   using System;
   using System.Collections.Generic;
   using System.Diagnostics;
   using System.Threading.Tasks;
   
   namespace AccessServicesWithOAuth
   {
   
       // A helper class that manages authenticating with a server to access secure resources.
       internal static class AuthenticationHelper
       {
           // Specify the Client ID and Redirect URL to use for OAuth authentication.
           // Sign in with your ArcGIS Location Platform or ArcGIS Online account
           // (https://www.arcgis.com/home/signin.html) to create your OAuth Application item.
   
           private const string OAuthClientID = "YOUR_CLIENT_ID";
           private const string OAuthRedirectUrl = "YOUR_REDIRECT_URL";
   
           static AuthenticationHelper()
           {
               // Use the OAuthAuthorize class (defined below) to show the login UI.
               AuthenticationManager.Current.OAuthAuthorizeHandler = new OAuthAuthorize();
   
               // Create a new ChallengeHandler that uses a method in this class to challenge for credentials.
               AuthenticationManager.Current.ChallengeHandler = new ChallengeHandler(PromptCredentialAsync);
           }
   
           // A function to register a secure server with the AuthenticationManager.
           // Pass in the URL of the server containing secure resources and, optionally, a client ID and
           // redirect URL (if not specified, the values defined above are used).
           public static void RegisterSecureServer(string url,
                                                   string clientID = OAuthClientID,
                                                   string redirectUrl = OAuthRedirectUrl)
           {
               // Define the server URL, authentication type, client ID, and redirect URL.
               ServerInfo portalServerInfo = new ServerInfo(new Uri(url))
               {
                   TokenAuthenticationType = TokenAuthenticationType.OAuthAuthorizationCode,
                   OAuthClientInfo = new OAuthClientInfo(clientID, new Uri(redirectUrl))
               };
   
               // Register the server information with the AuthenticationManager.
               AuthenticationManager.Current.RegisterServer(portalServerInfo);
           }
   
           // A function that adds a credential to AuthenticationManager based on a temporary token.
           // This is useful for testing an app with secured services without having to log in.
           public static void ApplyTemporaryToken(string url, string token)
           {
               // Create a new OAuth credential for the specified URL with the token.
               OAuthTokenCredential tempToken = new OAuthTokenCredential(new Uri(url), token);
   
               // Add the credential to the AuthenticationManager.
               AuthenticationManager.Current.AddCredential(tempToken);
           }
   
           // The ChallengeHandler function that is called when access to a secured resource is attempted.
           public static async Task<Credential> PromptCredentialAsync(CredentialRequestInfo info)
           {
               Credential credential = null;
   
               try
               {
                   // Get credentials for the specified server. The OAuthAuthorize class (defined below)
                   // will get the user's credentials (show the login window and handle the response).
                   credential = await AuthenticationManager.Current.GenerateCredentialAsync(info.ServiceUri);
               }
               catch (OperationCanceledException)
               {
                   // Login was cancelled, no need to display an error to the user.
               }
   
               return credential;
           }
   
           #region OAuth handler
   
           // In a .NET MAUI app, an IOAuthAuthorizeHandler component is used to handle some of
           // the OAuth details. Specifically, it implements AuthorizeAsync to show the login UI
           // (generated by the server that hosts secure content) in a WebAuthenticator. When the user
           // logs in successfully, cancels the login, or closes the window without continuing, the
           // IOAuthAuthorizeHandler is responsible for obtaining the authorization from the server
           // or raising an OperationCanceledException.
           public class OAuthAuthorize : IOAuthAuthorizeHandler
           {
               // Function to initiate an authorization request. It takes the URIs for: the secured service,
               // the authorization endpoint, and the redirect URI.
   #if MACCATALYST || IOS
               public Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
               {
                   // Use a TaskCompletionSource to track the completion of the authorization.
                   var tcs = new TaskCompletionSource<IDictionary<string, string>>();
                   Microsoft.Maui.ApplicationModel.MainThread.BeginInvokeOnMainThread(async () =>
                   {
                       try
                       {
                           var result = await WebAuthenticator.AuthenticateAsync(authorizeUri, callbackUri);
                           tcs.TrySetResult(result.Properties);
                       }
                       catch (Exception ex)
                       {
                           tcs.TrySetException(ex);
                       }
                   });
                   return tcs.Task;
               }
   #elif ANDROID
               public async Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
               {
                   var result = await WebAuthenticator.AuthenticateAsync(authorizeUri, callbackUri);
                   return result.Properties;
               }
   #elif WINDOWS
               // WebAuthenticator does not currently work on Windows without the WinUIEx library.
               // https://learn.microsoft.com/en-us/dotnet/maui/platform-integration/communication/authentication?tabs=windows
               public async Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
               {
                   var result = await WinUIEx.WebAuthenticator.AuthenticateAsync(authorizeUri, callbackUri);
   
                   return result.Properties;
               }
   
   #endif
   
   #if ANDROID
               // Android requires an Intent Filter setup to handle your callback URI.
               // This is accomplished by inheriting from the WebAuthenticatorCallbackActivity class.
               // https://learn.microsoft.com/en-us/dotnet/maui/platform-integration/communication/authentication?tabs=android
   
               [Activity(NoHistory = true, Exported = true, LaunchMode = LaunchMode.SingleTop)]
               [IntentFilter(new[] { Intent.ActionView },
                  Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
                  DataScheme = "my-app", DataHost = "auth")]
               public class WebAuthenticationCallbackActivity : WebAuthenticatorCallbackActivity
               {
               }
   
   #endif
   
               #endregion OAuth handler
   
           }
       }
   }

4. Near the top of the file, add your values for Client ID (OAuthClientID) and Redirect URL (OAuthRedirectUrl ). These were created with your OAuth application metadata in an earlier step and are unique to your application.

   AuthenticationHelper.cs

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
   100
   101
   102
   103
   104
   105
   106
   107
   108
   109
   110
   111
   112
   113
   114
   115
   116
   117
   118
   119
   120
   121
   122
   123
   124
   125
   126
   127
   128
   129
   130
   131
   132
   133
   134
   135
   136
   137
   138
   139
   140
   141
   142
   143
   144
   145
   146
   147
   148
   149
   150
   151
   152
   153
   154
   155
   156
   157
   158
   159
   160
   161
   162
   163
   164
   165
   166
   167
       // A helper class that manages authenticating with a server to access secure resources.
       internal static class AuthenticationHelper
       {
           // Specify the Client ID and Redirect URL to use for OAuth authentication.
           // Sign in with your ArcGIS Location Platform or ArcGIS Online account
           // (https://www.arcgis.com/home/signin.html) to create your OAuth Application item.
   
           private const string OAuthClientID = "YOUR_CLIENT_ID";
           private const string OAuthRedirectUrl = "YOUR_REDIRECT_URL";
   

The AuthenticationHelper class is now set up to handle OAuth authentication in your app. This class is generic enough that you can use it in any app, as long as valid client ID and redirect URL values are provided.

The last step is to use AuthenticationHelper to register one or more server URLs with AuthenticationManager to authenticate the user for secure resources from those servers.

Register ArcGIS Online for user authentication

Registering a portal with AuthenticationManager ensures that the user will be authenticated for any secured services on that portal. The portal is registered using its URL and the type of authentication it requires (one of the token authentication types supported for ArcGIS). For OAuth authentication, you must also provide OAuth Application item details, such as the Client ID and Redirect URL.

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

2. In the SetupMap() function, add a line of code that uses AuthenticationHelper to register ArcGIS Online for authentication.

   MapViewModel.cs

   Expand

   Use dark colors for code blocks

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
           private void SetupMap()
           {
   
               // Add the ArcGIS Online URL to the authentication helper.
               AuthenticationHelper.RegisterSecureServer("https://www.arcgis.com/sharing/rest");
   
               // Create a new map with a 'topographic vector' basemap.
               var trafficMap = new Map(BasemapStyle.ArcGISTopographic);
   
               var mapCenterPoint = new MapPoint(-118.805, 34.027, SpatialReferences.Wgs84);
   
               trafficMap.InitialViewpoint = new Viewpoint(mapCenterPoint, 100000);
   
               // Create a layer to display the ArcGIS World Traffic service.
               var trafficServiceUrl = "https://traffic.arcgis.com/arcgis/rest/services/World/Traffic/MapServer";
               var trafficLayer = new ArcGISMapImageLayer(new Uri(trafficServiceUrl));
   
               // Handle changes in the traffic layer's load status to check for errors.
               trafficLayer.LoadStatusChanged += TrafficLayer_LoadStatusChanged;
   
               // Add the traffic layer to the map's data layer collection.
               trafficMap.OperationalLayers.Add(trafficLayer);
   
               // Set the view model Map property with the new map.
               this.Map = trafficMap;
   
           }
   

   Expand

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

   More info

   If creating apps for Android or iOS, you will need the appropriate emulator, simulator, or device configured for testing (see System requirements for details)

You should again see a map with the topographic basemap layer centered on the Santa Monica Mountains in California. You will be prompted for an ArcGIS Online username and password. Once you authenticate successfully with ArcGIS Online, the traffic layer will appear in the map.

Testing apps that require authentication

When you are testing apps that require authentication for one or more services in the map, it can become monotonous to enter your OAuth credentials repeatedly. You can programmatically add authentication for a server using the temporary token provided with your OAuth Application item details. As the name suggests, this token is valid for a limited time, but you can always get a fresh token from ArcGIS.com using your ArcGIS Account.

The AuthenticationHelper has the following function for applying a temporary token.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
        // A function that adds a credential to AuthenticationManager based on a temporary token.
        // This is useful for testing an app with secured services without having to log in.
        public static void ApplyTemporaryToken(string url, string token)
        {
            // Create a new OAuth credential for the specified URL with the token.
            OAuthTokenCredential tempToken = new OAuthTokenCredential(new Uri(url), token);

            // Add the credential to the AuthenticationManager.
            AuthenticationManager.Current.AddCredential(tempToken);
        }

You can call the function with code such as:

1
   AuthenticationHelper.ApplyTemporaryToken("https://www.arcgis.com/sharing/rest", "YOUR_TEMP_TOKEN");

Until the token expires, you can run the app without being challenged to provide your credentials.

Additional resources

If you are implementing OAuth for another .NET platform, you might find some of the following resources helpful.

• ArcGIS Maps SDK for .NET OAuth sample: The WPF version of this sample uses code similar to code used in this tutorial. The sample is available for other .NET platforms (use the switcher control at the top of the page) to illustrate implementing OAuth for apps targeting WinUI, UWP, and .NET MAUI.
• Web authentication broker: Use this authentication broker to implement OAuth in your Universal Windows Platform (UWP) apps.