This project demonstrates how to request and manage device permissions in a MAUI Blazor app. Handling permissions requests is a requirement for accessing APIs that rely on certain device features (location, camera, microphone, etc.).
MainPage.xaml.cs registers handlers for BlazorWebView.BlazorWebViewInitializing and BlazorWebView.BlazorWebViewInitialized. These events are used to perform platform-specific WebView configuration, so this project uses them to enable web APIs that are restricted by default. The event handlers are defined in MainPage.xaml.Windows.cs for Windows, MainPage.xaml.Android.cs for Android, and MainPage.xaml.iOS.cs for iOS/Mac Catalyst.
Additional platform-specific permission management code and configuration files live in the Platforms/ folders.
The rest is fairly standard, with pages in the Pages/ folder and JavaScript in wwwroot/js/.
This example app demonstrates accessing the device's location, camera, and microphone from JavaScript web APIs, but you can easily add more supported permissions to fit the needs of your app. The following sections describe the steps necessary to support additional types of permissions on each platform.
App capabilities are listed in Package.appxmanifest. The .NET MAUI Blazor App project template includes the capability "runFullTrust" so individual capabilities do not need to be listed manually. See the official docs for more information about app capability declarations.
Permissions and features required by the app are defined in AndroidManifest.xml. See the official docs to learn about the Android App Manifest.
Certain Android device permissions require a prompt to be shown at runtime so the user can grant or deny the permission. Android has a recommended workflow for requesting permissions at runtime, and this workflow must be implemented by the app manually. The WebView's WebChromeClient is responsible for reacting to permission requests, so this project provides a PermissionManagingBlazorWebChromeClient that maps Webkit resources to Android permissions and executes the recommended workflow for requesting permissions.
After adding additional permissions to AndroidManifest.xml, be sure to update PermissionManagingBlazorWebChromeClient.cs to include a "rationale string" for that permission explaining why it is needed by the app. It may also be necessary to define additional mappings between permission request types and Android Manifest permissions.
iOS device permissions are defined by adding entries in Info.plist containing descriptions justifying why each permission is necessary. See NSLocationWhenInUseUsageDescription as an example.
The Windows implementation of this project supports two possible behaviors for permission management:
- Automatically grant all permission requests originating from the app origin, denying everything else
- Display a dialog when previously-ungranted permissions are being requested, allowing the user to decide whether to grant or deny
These two behaviors can be toggled using the HANDLE_WEBVIEW2_PERMISSIONS_SILENTLY constant, which is defined in MauiBlazorPermissionsExample.csproj.