.NET MAUI SDK setup

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.

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

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).

If your organization already has a OneSignal account, ask to be invited as an admin role to configure the app. Otherwise, sign up for a free account to get started.

Step-by-step instructions for configuring your OneSignal app.

You can manage multiple platforms (iOS, Android, Huawei, Amazon, Web) under a single OneSignal app.

Create or select your app

To add platforms to an existing app, go to Settings > Push & In-App in the OneSignal dashboard.
To start fresh, click New App/Website and follow the prompts.

Set up and activate a platform

Choose a clear and recognizable name for your app and organization.
Select the platform(s) you want to configure (iOS, Android, etc.).
Click Next: Configure Your Platform.

Configure platform credentials

Follow the prompts based on your platforms:

Android: Set up Firebase Credentials
iOS: p8 Token (Recommended) or p12 Certificate
Amazon: Generate API Key
Huawei: Authorize OneSignal

Click Save & Continue after entering your credentials.

Choose target SDK

Select the SDK that matches your development platform (e.g., iOS, Android, React Native, Unity), then click Save & Continue.

Install SDK and save your App ID

Once your platform is configured, your OneSignal App ID will be displayed. Copy and save this ID—you’ll need it when installing and initializing the SDK.If collaborating with others, use the Invite button to add developers or teammates, then click Done to complete setup.

Once complete, follow the SDK installation guide for your selected platform to finish integrating OneSignal.

SDK Setup

1. Add SDK

Using the .NET CLI:

bash

  dotnet add package OneSignalSDK.DotNet

2. Initialize SDK

Xamarin Forms is no longer supported beyond version 5.0.2 of our .NET SDK. Microsoft has guides on migrating to Maui here, if needed.

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

If you don’t have access to the OneSignal app, ask your Team Members to invite you.

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();
}

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);
        }
    }
}

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.

After confirming that your Android build works:

Continue with the iOS setup, if applicable.
Or jump ahead to Testing the OneSignal SDK integration.

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.

1. Add Push Notifications capability to app target

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

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

2. Add Background Modes capability to app target

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

Add Background Modes capability
Enable Remote notifications

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.

If you do NOT have an App Group configured
If you DO have an App Group

Add App Groups capability
In the App Groups capability click +
Add a new container ID in format: group.your_bundle_id.onesignal

Keep group. and .onesignal prefix and suffix. Replace your_bundle_id with your app’s bundle identifier.
For example, bundle identifier com.onesignal.MyApp, will have the container name group.com.onesignal.MyApp.onesignal.

Your App Group name must exactly match your bundle ID’s spelling and capitalization across all targets.

Open your App Target and OneSignalNotificationServiceExtension Target’s Info.plist
Add a new property to the Info.plist for both targets:

Key: OneSignal_app_groups_key
Value: Your existing App Group name (e.g., group.your-custom-group-id)

XML

<key>OneSignal_app_groups_key</key>
<string>group.your-custom-group-id</string>

Make sure to update the OneSignal_app_groups_key in both the App Target and OneSignalNotificationServiceExtension Target’s Info.plist!

4. Add Notification Service Extension

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

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

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

If you’re using CocoaPods, set the deployment version in your Podfile as well.

5. Add NSE target to app group

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

Go to OneSignalNotificationServiceExtension > Signing & Capabilities
Add App Groups
Add the exact same group ID

If you are using a custom App Group name and not group.your_bundle_id.onesignal then make sure to add your App Group ID to both the App Target and OneSignalNotificationServiceExtension Target’s Info.plist! See step 3 for more information.

6. Update NSE code

Navigate to the OneSignalNotificationServiceExtension folder
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.

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:

shell

cd ios pod install cd ..

Common pod install errors

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

ArgumentError - \[Xcodeproj] Unable to find compatibility version string for object version `70`.

CocoaPods relies on the xcodeproj Ruby gem to read your Xcode project files. As of now, the latest xcodeproj release does not recognize object version 70, which was introduced by Xcode 16. So when CocoaPods tries to open your .xcodeproj file, it crashes with this error.

Close Xcode.
Navigate to your project’s ios/<your-app>.xcodeproj/project.pbxproj file.
Change this line: objectVersion = 70;
Replace it with: objectVersion = 55;
Save, close, and rerun cd ios pod install cd ..

Build for iOS

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

Common iOS build errors

commandPhaseScript Execution exited with a non-zero code

Delete your Podfile.lock
Delete your Pods folder
Delete your .xcworkspace
Pod install
Cmd + Shift + K to Clean the build and then retry building

If these steps do not resolve the error, build directly from the Xcode, then find the build error in the report navigator pictured below.

Cycle Inside... building could produce unreliable results.

You may see this error when building with Xcode 15+, due to a default configuration change affecting cross platform systems.

Open your .xcworkspace folder in Xcode and navigate to your app target > Build Phases.
You should have a phase called “Embed Foundation Extensions” or “Embed App Extensions”.
Drag and move this build phase to above “Run Script”.
Build and run your app. The error should be resolved.

PBXGroup Error

RuntimeError - PBXGroup attempted to initialize an object with unknown ISA PBXFileSystemSynchronizedRootGroup from attributes:

{"isa"=>"...", "exceptions"=>["//", "..."], "explicitFileTypes"=>{}, "explicitFolders"=>[], "path"=>"OneSignalNotificationServiceExtension", "sourceTree"=>"<group>"}

Fix:

Find the folder listed under “path” in the error
In Xcode project sidebar, right-click the folder
Select Convert to Group

After confirming that your iOS build works, continue with Testing the OneSignal SDK integration.

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.

If you are testing with an Android emulator, it should start with a cold boot.

Go to Device Manager in Android Studio.
Select your emulator device and click Edit.
Go to Additional Settings or More.
Set the Boot option to Cold Boot.
Save changes and restart the emulator.

Check mobile subscriptions

Launch your app on a test device.

The native push permission prompt should appear automatically if you added the requestPermission method during initialization.

Check your OneSignal dashboard

Before accepting the prompt, check the OneSignal dashboard:

Go to Audience > Subscriptions.
You should see a new entry with the status “Never Subscribed”.

Return to the app and tap Allow on the prompt.

Refresh the OneSignal dashboard Subscription's page.

The subscription’s status should now show Subscribed.

You have successfully created a mobile subscription. Mobile subscriptions are created when users first open your app on a device or if they uninstall and reinstall your app on the same device.

Set up test subscriptions

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

Add to Test Subscriptions.

In the dashboard, next to the subscription, click the Options (three dots) button and select Add to Test Subscriptions.

Name your subscription.

Name the subscription so you can easily identify your device later in the Test Subscriptions tab.

Create a test users segment.

Go to Audience > Segments > New Segment.

Name the segment.

Name the segment Test Users (the name is important because it will be used later).

Add the Test Users filter and click Create Segment.

You have successfully created a segment of test users. We can now test sending messages to this individual device and groups of test users.

Send test push via API

Get your App API Key and App ID.

In your OneSignal dashboard, go to Settings > Keys & IDs.

Update the provided code.

Replace YOUR_APP_API_KEY and YOUR_APP_ID in the code below with your actual keys. This code uses the Test Users segment we created earlier.

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"
}'

Run the code.

Run the code in your terminal.

Check images and confirmed delivery.

If all setup steps were completed successfully, the test subscriptions should receive a notification with an image included:

Images will appear small in the collapsed notification view. Expand the notification to see the full image.

Check for confirmed delivery.

In your dashboard, go to Delivery > Sent Messages, then click the message to view stats.You should see the confirmed stat, meaning the device received the push.

If you’re on a Professional plan or higher, scroll to Audience Activity to see subscription-level confirmation:

You have successfully sent a notification via our API to a segment.

No image received? Your Notification Service Extension might be missing.
No confirmed delivery? Review the troubleshooting guide here.
Having issues? Copy-paste the api request and a log from start to finish of app launch into a .txt file. Then share both with [email protected].

Send an in-app message

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

Close or background your app on the device.

This is because users must meet the in-app audience criteria before a new session starts. In OneSignal, a new session starts when the user opens your app after it has been in the background or closed for at least 30 seconds. For more details, see our guide on how in-app messages are displayed.

Create an in-app message.

In your OneSignal dashboard, navigate to Messages > In-App > New In-App.
Find and select the Welcome message.
Set your Audience as the Test Users segment we used previously.

Customize the message content if desired.

Set Trigger to 'On app open'.

Schedule frequency.

Under Schedule > How often do you want to show this message? select Every time trigger conditions are satisfied.

Make message live.

Click Make Message Live so it is available to your Test Users each time they open the app.

Open the app and see the message.

After the in-app message is live, open your app. You should see it display:

Not seeing the message?

Start a new session
- You must close or background the app for at least 30 seconds before reopening. This ensures a new session is started.
- For more, see how in-app messages are displayed.
Still in the Test Users segment?
- If you reinstalled or switched devices, re-add the device to Test Subscriptions and confirm it’s part of the Test Users segment.
Having issues?
- Follow Getting a Debug Log while reproducing the steps above. This will generate additional logging that you can share with [email protected] and we will help investigate what’s going on.

You have successfully setup the OneSignal SDK and learned important concepts like:

Gathering Subscriptions, setting Test subscriptions, and creating Segments.
Sending Push with images and Confirmed Delivery using Segments and our Create message API.
Sending In-app messages.

Continue with this guide to identify users in your app and setup additional features.

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.

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.

OneSignal generates unique read-only IDs for subscriptions (Subscription ID) and users (OneSignal ID).As users download your app on different devices, subscribe to your website, and/or provide you email addresses and phone numbers outside of your app, new subscriptions will be created.Setting the External ID via our SDK is highly recommended to identify users across all their subscriptions, regardless of how they are created.

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:

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.

Best practices for multi-channel communication

Obtain explicit consent before adding email or SMS subscriptions.
Explain the benefits of each communication channel to users.
Provide channel preferences so users can select which channels they prefer.

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:

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.

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.

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.

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.

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.).

Advanced setup & capabilities

Explore more capabilities to enhance your integration:

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.

Congratulations! You’ve successfully completed the Mobile SDK setup guide.

Need help?Chat with our Support team or email [email protected]Please include:

Details of the issue you’re experiencing and steps to reproduce if available
Your OneSignal App ID
The External ID or Subscription ID if applicable
The URL to the message you tested in the OneSignal Dashboard if applicable
Any relevant logs or error messages

We’re happy to help!

Developer Documentation

Mobile SDKs

Web SDKs

Live Activities

Desktop & Watch Setup

Legacy SDK reference

​Overview

​Requirements

​Configure your OneSignal app and platform

​SDK Setup

​1. Add SDK

​2. Initialize SDK

​3. Adding an iOS Service Extension

​Android setup

​iOS setup

​1. Add Push Notifications capability to app target

​2. Add Background Modes capability to app target

​3. Add app target to App Group

​4. Add Notification Service Extension

​5. Add NSE target to app group

​6. Update NSE code

​7. Add OneSignal to the NSE target

​Common pod install errors

​Build for iOS

​Common iOS build errors

​Testing the OneSignal SDK integration

​Check mobile subscriptions

​Set up test subscriptions

​Send test push via API

​Send an in-app message

​User identification

​Assign External ID

​Add data tags

​Add email and/or SMS subscriptions

​Privacy & user consent

​Prompt for push permissions

​Listen to push, user, and in-app events

​Push notification events

​User state changes

​In-app message events

​Advanced setup & capabilities

​Mobile SDK setup & reference

Overview

Requirements

Configure your OneSignal app and platform

SDK Setup

1. Add SDK

2. Initialize SDK

3. Adding an iOS Service Extension

Android setup

iOS setup

1. Add Push Notifications capability to app target

2. Add Background Modes capability to app target

3. Add app target to App Group

4. Add Notification Service Extension

5. Add NSE target to app group

6. Update NSE code

7. Add OneSignal to the NSE target

Common pod install errors

Build for iOS

Common iOS build errors

Testing the OneSignal SDK integration

Check mobile subscriptions

Set up test subscriptions

Send test push via API

Send an in-app message

User identification

Assign External ID

Add data tags

Add email and/or SMS subscriptions

Privacy & user consent

Prompt for push permissions

Listen to push, user, and in-app events

Push notification events

User state changes

In-app message events

Advanced setup & capabilities

Mobile SDK setup & reference