> This page is part of the [Customer.io documentation](https://docs.customer.io). For the complete index, see [llms.txt](https://docs.customer.io/llms.txt).
> Last updated: July 8, 2026

# 2.x -> 3.0.0

Version 3.x of the Customer.io Flutter SDK introduces Firebase wrapper support for FCM users that improves Firebase compatibility and simplifies push notification setup.

## What changed?

Version 3.x introduces a Firebase wrapper that improves compatibility with Firebase Cloud Messaging (FCM).

## What needs to change?

You need to add the `CioFirebaseWrapper` import to your Swift files that use `CioMessagingPushFCM`.

Add the Firebase wrapper import to your `AppDelegate.swift` file:

```swift
import UIKit
import Flutter
import CioMessagingPushFCM
import CioFirebaseWrapper  // Add this import for FCM users
import FirebaseMessaging
import FirebaseCore

@main
class AppDelegateWithCioIntegration: CioAppDelegateWrapper<AppDelegate> {}
```

## Troubleshooting

If you see build errors related to Firebase after upgrading:

1.  **Clean your build**: Run `cd ios && pod install && cd ..` then rebuild
2.  **Check imports**: Ensure you’ve added `import CioFirebaseWrapper` to all files that import `CioMessagingPushFCM`

Version[](https://github.com/customerio/customerio-flutter/releases/tag/4.1.2 "See this release in GitHub")

4.1.2 (Current)2.9.01.5.2

*   *   [What changed?](#what-changed)
    *   [What needs to change?](#what-needs-to-change)
    *   [Troubleshooting](#troubleshooting)

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