Always forward received UNNotifications

to an overridden user delegate, even before the messaging SDK is initialized.

Description

Provide details of the change, and generalize the change in the PR title above.

messaging.mm sets up a UNUserNotificationCenterDelegate in RequestPermission. If any other delegate was already set, it is designed to forward incoming notifications to the previous delegate in -[UIApplication userNotificationCenter:didReceiveNotificationResponse:withCompletionHandler:]. However, RequestPermission may be called before Messaging is initialized, in which case these notifications were not being forwarded. If any user notifications come in before Firebase Messaging is initialized, the notification is lost.

This is the cause of https://github.com/firebase/firebase-unity-sdk/issues/377 as well as https://github.com/Unity-Technologies/com.unity.mobile.notifications/issues/316

Notifications should now be forwarded to the overridden delegate, whether Messaging is initialized or not.

Type of Change

Place an x the applicable box:

[X] Bug fix. Add the issue # below if applicable.
[ ] New feature. A non-breaking change which adds functionality.
[ ] Other, such as a build process or documentation change.

firebase / firebase-cpp-sdk

Always forward received UNNotifications #1604

Description

Type of Change

✅ Integration test succeeded!