Hi. My MacOS application (Obj-C, Cocoa MacOS 10.15 or later) sets itself as delegate for UNNotificationCenter, and implements both
- (void)userNotificationCenter:(UNUserNotificationCenter *)center
willPresentNotification:(UNNotification *)notification
withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler
and
- (void)userNotificationCenter:(UNUserNotificationCenter *)center
didReceiveNotificationResponse:(nonnull UNNotificationResponse *)response
withCompletionHandler:(nonnull void (^)(void))completionHandler
It creates and schedules many user-notifications (mostly with no "trigger" meaning - present to the user ASAP and sometimes 2.5 seconds in the future, so to group notifications better.
Each notification is also holding som dictionary of "UserInfo" containing some data. My AppDelegates handles user responses (both standard open, cancellation, and "cancel-all") and also custom user-actions I attach to the category.
All works well on most Macs and almost always.
However -
On few Macs, at arbitrary times, users complain that "clicking a notification in Notification Center will not open the app" and that "expected notifications are missing altogether".
My logs show the following. Quite frequently I see the following: error log lines:
2023-02-16 17:32:21.413065+0200 0xa58109d Error 0x0 51690 0 <UserNotifications`__104-[UNUserNotificationServiceConnection addNotificationRequest:forBundleIdentifier:withCompletionHandler:]_block_invoke_2.cold.1> myApp: (UserNotifications) [com.apple.UserNotifications:Connections] [com.myCompany.myApp] Adding notification request failed with error: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service on pid 451 named com.apple.usernotifications.usernotificationservice" UserInfo={NSDebugDescription=connection to service on pid 451 named com.apple.usernotifications.usernotificationservice}
followed by my own log lines - like this:
2023-02-16 17:32:21.413279+0200 0xa5811b5 Error 0x0 51690 10 <myApp> myApp: [com.myCompany.myApp:UI] NotificationRequest B6096CDE-6229-42AA-A6BC-EBCC06540C53 stage:scanFinished failed to schedule: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service on pid 451 named com.apple.usernotifications.usernotificationservice" UserInfo={NSDebugDescription=connection to service on pid 451 named com.apple.usernotifications.usernotificationservice}
Of course - the un-scheduled notification won't appear to the user, but worse - clicks on other, DELIVERED notifications, won't call back my delegate.
Strangely enough - few seconds later, sometimes minutes - other attempts to schedule new notifications - succeed without any error. I guess this "connection" is somehow automatically re-established.
I looked for information about this error (Domain=NSCocoaErrorDomain Code=4097) and it seems to be pretty generic, and used for many scenarios where connection to some service is lost.
Of course my code doesn't maintain any such connection manually/programmatically - I guess it is the [UNUserNotificationCenter currentNotificationCenter] implementation which holds connection to its "daemon" or "agent" or some XPC service.
The really bad thing here - is that I DO NOT KNOW how to improve anything here.
[UNUserNotificationCenter currentNotificationCenter]Is a singleton, that I can't control, or re-create, to somehow revive the connection- There is no way I know of, to tell it to do so, or even to check whether it has a connection.
- I rely on Notification-Center to maintain my MODEL DATA for scheduled requests, in case my App is relaunched - and now I can't get it.
Please advise. this is quite urgent for me.
The issue appears more on Big Sur.