.NET MAUI SDK setup

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Overview

This guide explains how to integrate OneSignal push notifications into a .NET MAUI application. It covers everything from installation to configuration and service worker management.

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Requirements

• .NET 7.0+
• Visual Studio 2019 or newer
• Configured OneSignal app and platform

iOS Requirements

• macOS with Xcode 14+ (setup instructions use Xcode 16.2)
• Device with iOS 12+, iPadOS 12+, or Xcode simulator running iOS 16.2+
• CocoaPods 1.16.2+

Android Requirements

• Android 7.0+ device or emulator with Google Play Store (Services) installed

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Configure your OneSignal app and platform

Required setup for push notifications

To start sending push notifications with OneSignal, you must first configure your OneSignal app with all the platforms your support—Apple (APNs), Google (FCM), Huawei (HMS), and/or Amazon (ADM).

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SDK Setup

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1. Add SDK

Using the .NET CLI:

  dotnet add package OneSignalSDK.DotNet

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2. Initialize SDK

Initialize OneSignal in App.xaml.cs file.

Replace YOUR_APP_ID with your OneSignal App ID found in your OneSignal dashboard Settings > Keys & IDs.

using OneSignalSDK.DotNet;
using OneSignalSDK.DotNet.Core;
using OneSignalSDK.DotNet.Core.Debug;

public App() {
  InitializeComponent();
  
  // Enable verbose OneSignal logging to debug issues if needed.
  OneSignal.Debug.LogLevel = LogLevel.VERBOSE;

  // OneSignal Initialization
  OneSignal.Initialize("YOUR_APP_ID");
  
  // RequestPermissionAsync will show the notification permission prompt.
  // We recommend removing the following code and instead using an In-App Message to prompt for notification permission (See step 5)
  OneSignal.Notifications.RequestPermissionAsync(true);

  MainPage = new AppShell();
}

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3. Adding an iOS Service Extension

Microsoft has a guide on generating a Notification Service Extension here, using Visual Studio and Visual Studio for Mac, but does not have any guidance on how you would create this for VSCode at this time.

If you generate a service extension following the guide above, you can follow this the code in our sample project found on Github

using System;
using Foundation;
using OneSignalSDK.DotNet;
using OneSignalSDK.DotNet.iOS;
using UIKit;
using UserNotifications;

namespace OneSignalNotificationServiceExtension
{
    [Register("NotificationService")]
    public class NotificationService : UNNotificationServiceExtension
    {
        Action<UNNotificationContent> ContentHandler { get; set; }
        UNMutableNotificationContent BestAttemptContent { get; set; }
        UNNotificationRequest ReceivedRequest { get; set; }

        protected NotificationService(IntPtr handle) : base(handle)
        {
            // Note: this .ctor should not contain any initialization logic.
        }

        public override void DidReceiveNotificationRequest(UNNotificationRequest request, Action<UNNotificationContent> contentHandler)
        {
            ReceivedRequest = request;
            ContentHandler = contentHandler;
            BestAttemptContent = (UNMutableNotificationContent)request.Content.MutableCopy();

            NotificationServiceExtension.DidReceiveNotificationExtensionRequest(request, BestAttemptContent, contentHandler);
        }

        public override void TimeWillExpire()
        {
            // Called just before the extension will be terminated by the system.
            // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.

            NotificationServiceExtension.ServiceExtensionTimeWillExpireRequest(ReceivedRequest, BestAttemptContent);

            ContentHandler(BestAttemptContent);
        }
    }
}

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Android setup

Make sure your OneSignal app is configured for the Android platform using your Firebase credentials.

Set up your notification icons to match your app’s branding. If this step is skipped, a default bell icon will display for your push notifications.

Build for Android

At this point, you should be able to build and run your app on a physical Android device or emulator without issues.

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iOS setup

Make sure your OneSignal app is configured for the iOS platform using either the p8 Token (Recommended) or p12 Certificate.

Follow these steps to add push notifications to your iOS app, including support for Badges, Confirmed Delivery, and images.

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1. Add Push Notifications capability to app target

The Push Notifications capability allows your app to register a push token and receive notifications.

1. Open your app’s .xcworkspace file in Xcode.
2. Select your app target > Signing & Capabilities
3. Click + Capability and add Push Notifications capability

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2. Add Background Modes capability to app target

This enables your app to wake in the background when push notifications arrive.

1. Add Background Modes capability
2. Enable Remote notifications

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3. Add app target to App Group

App Groups allow data sharing between your app and the Notification Service Extension. Required for Confirmed Delivery and Badges.

<key>OneSignal_app_groups_key</key>
<string>group.com.example.mycustomgroup</string>

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4. Add Notification Service Extension

The Notification Service Extension (NSE) enables rich notifications and Confirmed Delivery analytics.

1. In Xcode: File > New > Target…
2. Select Notification Service Extension, then Next.
3. Set the product name to OneSignalNotificationServiceExtension and press Finish.
4. Press Don’t Activate on the Activate scheme prompt.

Set the OneSignalNotificationServiceExtension Minimum Deployment Target to match your main app (iOS 15+ recommended).

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5. Add NSE target to app group

Use the same App Group ID you added in step 3.

1. Go to OneSignalNotificationServiceExtension > Signing & Capabilities
2. Add App Groups
3. Add the exact same group ID

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6. Update NSE code

1. Navigate to the OneSignalNotificationServiceExtension folder
2. Replace the contents of the NotificationService.swift or NotificationService.m file with the following:

import UserNotifications
import OneSignalExtension

class NotificationService: UNNotificationServiceExtension {
    var contentHandler: ((UNNotificationContent) -> Void)?
    var receivedRequest: UNNotificationRequest!
    var bestAttemptContent: UNMutableNotificationContent?

    // Note this extension only runs when `mutable_content` is set
    // Setting an attachment or action buttons automatically sets the property to true
    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.receivedRequest = request
        self.contentHandler = contentHandler
        self.bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)

        if let bestAttemptContent = bestAttemptContent {
            // DEBUGGING: Uncomment the 2 lines below to check this extension is executing
//            print("Running NotificationServiceExtension")
//            bestAttemptContent.body = "[Modified] " + bestAttemptContent.body

            OneSignalExtension.didReceiveNotificationExtensionRequest(self.receivedRequest, with: bestAttemptContent, withContentHandler: self.contentHandler)
        }
    }

    override func serviceExtensionTimeWillExpire() {
        // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            OneSignalExtension.serviceExtensionTimeWillExpireRequest(self.receivedRequest, with: self.bestAttemptContent)
            contentHandler(bestAttemptContent)
        }
    }
}

You should see an error because the OneSignal package is not installed. This will be resolved in the next step.

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7. Add OneSignal to the NSE target

Update your ios/Podfile to include:

target 'OneSignalNotificationServiceExtension' do
  pod 'OneSignalXCFramework', '>= 5.0.0', '< 6.0'
end

Open your project in the terminal and run:

cd ios pod install cd .. 

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Common pod install errors

You may run into the following errors, here is how you can resolve them.

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Build for iOS

You should now be able to build and run your app on a real iOS device or iOS simulator (16.2+).

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Common iOS build errors

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Testing the OneSignal SDK integration

This guide helps you verify that your OneSignal SDK integration is working correctly by testing push notifications, subscription registration, and in-app messaging.

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Check mobile subscriptions

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Set up test subscriptions

Test subscriptions are helpful for testing a push notification before sending a message.

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Send test push via API

curl -X \
POST --url 'https://api.onesignal.com/notifications' \
 --header 'content-type: application/json; charset=utf-8' \
 --header 'authorization: Key YOUR_APP_API_KEY' \
 --data \
 '{
  "app_id": "YOUR_APP_ID",
  "target_channel": "push",
  "name": "Testing basic setup",
  "headings": {
  	"en": "👋"
  },
  "contents": {
    "en": "Hello world!"
  },
  "included_segments": [
    "Test Users"
  ],
  "ios_attachments": {
    "onesignal_logo": "https://avatars.githubusercontent.com/u/11823027?s=200&v=4"
  },
  "big_picture": "https://avatars.githubusercontent.com/u/11823027?s=200&v=4"
}'

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Send an in-app message

In-app messages let you communicate with users while they are using your app.

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User identification

Previously, we demonstrated how to create mobile Subscriptions. Now we’ll expand to identifying Users across all their subscriptions (including push, email, and SMS) using the OneSignal SDK. We’ll cover External IDs, tags, multi-channel subscriptions, privacy, and event tracking to help you unify and engage users across platforms.

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Assign External ID

Use an External ID to identify users consistently across devices, email addresses, and phone numbers using your backend’s user identifier. This ensures your messaging stays unified across channels and 3rd party systems (especially important for Integrations).

Set the External ID with our SDK’s login method each time they are identified by your app.

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Add data tags

Tags are key-value pairs of string data you can use to store user properties (like username, role, or preferences) and events (like purchase_date, game_level, or user interactions). Tags power advanced Message Personalization and Segmentation allowing for more advanced use cases.

Set tags with our SDK addTag and addTags methods as events occur in your app.

In this example, the user reached level 6 identifiable by the tag called current_level set to a value of 6.

We can create a segment of users that have a level of between 5 and 10, and use that to send targeted and personalized messages:

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Add email and/or SMS subscriptions

Earlier we saw how our SDK creates mobile subscriptions to send push and in-app messages. You can also reach users through emails and SMS channels by creating the corresponding subscriptions.

• Use the addEmail method to create email subscriptions.
• Use the addSms method to create SMS subscriptions.

If the email address and/or phone number already exist in the OneSignal app, the SDK will add it to the existing user, it will not create duplicates.

You can view unified users via Audience > Users in the dashboard or with the View user API.

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Privacy & user consent

To control when OneSignal collects user data, use the SDK’s consent gating methods:

• setConsentRequired(true): Prevents data collection until consent is given.
• setConsentGiven(true): Enables data collection once consent is granted.

See our Privacy & security docs for more on:

• Data collected by the SDK
• Handling personal data

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Prompt for push permissions

Instead of calling requestPermission() immediately on app open, take a more strategic approach. Use an in-app message to explain the value of push notifications before requesting permission.

For best practices and implementation details, see our Prompt for push permissions guide.

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Listen to push, user, and in-app events

Use SDK listeners to react to user actions and state changes.

The SDK provides several event listeners for you to hook into. See our SDK reference guide for more details.

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Push notification events

• addClickListener(): Detect when a notification is tapped. Helpful for Deep Linking.
• addForegroundLifecycleListener(): Control how notifications behave in foreground.

For full customization, see Mobile Service Extensions.

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User state changes

• addObserver() for user state: Detect when the External ID is set.
• addPermissionObserver(): Track the user’s specific interaction with the native push permission prompt.
• addObserver() for push subscription: Track when the push subscription status changes.

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In-app message events

• addClickListener(): Handle in-app click actions. Ideal for deep linking or tracking events.
• addLifecycleListener(): Track full lifecycle of in-app messages (shown, clicked, dismissed, etc.).

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Advanced setup & capabilities

Explore more capabilities to enhance your integration:

• 🔁 Migrating to OneSignal from another service
• 🌍 Location tracking
• 🔗 Deep Linking
• 🔌 Integrations
• 🧩 Mobile Service Extensions
• 🛎️ Action buttons
• 🌐 Multi-language messaging
• 🛡️ Identity Verification
• 📊 Custom Outcomes
• 📲 Live Activities

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Mobile SDK setup & reference

Make sure you’ve enabled all key features by reviewing the Mobile push setup guide.

For full details on available methods and configuration options, visit the Mobile SDK reference.