iOS: $push_notification_opened not captured (warm or cold start) when flutter_local_notifications owns the notification delegate

[jimnaylor]

Summary

Push token registration works end to end (device token registers, Workflows pushes deliver via the APNs channel), but $push_notification_opened is never captured when the user taps a delivered push — on neither warm start (app backgrounded) nor cold start (app force-quit). Application Opened and the rest of the session capture normally, so it isn't a flush/ingestion issue: the open event simply never fires.

Environment

• posthog_flutter 5.39.0 (native posthog-ios resolved via the podspec pin >= 3.70.0, < 4.0.0)
• Flutter (stable), iOS device build distributed via TestFlight
• flutter_local_notifications 22.x in the same app — it calls UNUserNotificationCenter.current().delegate = self during its initialize() (used for locally scheduled reminders)
• PostHog config: defaults — enableSwizzling, capturePushNotificationSubscriptions, capturePushNotificationOpened all true; EU instance
• Push sent through a PostHog Workflows function_push step over a connected APNs channel (so title/body should be attachable)

Repro

1. App with both posthog_flutter 5.39.0 and flutter_local_notifications 22.x initialized (FLN sets the UNUserNotificationCenter delegate).
2. Register device token via the automatic subscription path (works — token registers, $device_push_subscription_<bundle_id> person property appears).
3. Send a push via a Workflows push step (delivery confirmed: "Push notification accepted by APNs" in workflow logs; notification arrives).
4. Tap the notification — tested both with the app backgrounded and fully force-quit.

Expected: $push_notification_opened captured.
Actual: no $push_notification_opened ever appears (project-wide count is zero). Application Opened from the same tap session arrives normally.

Suspicion

Reading PushNotificationPublisher in posthog-ios, the swizzling covers both the delegate-setter and an already-set delegate's userNotificationCenter(_:didReceive:withCompletionHandler:), so the FLN pairing looks like it should be handled — but with FLN as the delegate the response never reaches the publisher in practice. The Flutter changelog for the push release notes that the manual capturePushNotificationOpened API exists for "paths auto-detection cannot see"; in this configuration that appears to be all paths.

Happy to test a fix or provide more detail (delegate setup order, timestamps, workflow/invocation IDs) if useful.

[dustinbyrne]

thanks for the issue @jimnaylor - a couple of related items in progress here:

• feat(push): capture a launch intent the SDK was installed too late to read posthog-android#753
• feat(push): hold a notification tap that arrives before setup() posthog-ios#792

[turnipdabeets]

Filed the Android counterpart as #558 — the same symptom, different mechanism (the native SDK reads the launch intent in onActivityCreated, which a Flutter app installs too late to see; AUTO_INIT does not help there, unlike on iOS).

This issue now tracks the iOS half only, so that closing it doesn't leave the Android work untracked.

• iOS: this issue — feat(push): hold a notification tap that arrives before setup() posthog-ios#792 + fix(push): capture $push_notification_opened on iOS cold start #556
• Android: Android: $push_notification_opened not captured on a notification tap #558 — feat(push): capture a launch intent the SDK was installed too late to read posthog-android#753 + fix(push): capture $push_notification_opened on Android cold and warm start #557