I've been seeing a high number of BGTaskScheduler related crashes, all of them coming from iOS 18.4. I've encountered this myself once on launch upon installing my app, but haven't been able to reproduce it since, even after doing multiple relaunches and reinstalls. Crash report attached at the bottom of this post.
I am not even able to symbolicate the reports despite having the archive on my MacBook:
Does anyone know if this is an iOS 18.4 bug or am I doing something wrong when scheduling the task? Below is my code for scheduling the background task on the view that appears when my app launches:
.onChange(of: scenePhase) { newPhase in
if newPhase == .active {
#if !os(macOS)
let request = BGAppRefreshTaskRequest(identifier: "notifications")
request.earliestBeginDate = Calendar.current.date(byAdding: .hour, value: 3, to: Date())
do {
try BGTaskScheduler.shared.submit(request)
Logger.notifications.log("Background task scheduled. Earliest begin date: \(request.earliestBeginDate?.description ?? "nil", privacy: .public)")
} catch let error {
// print("Scheduling Error \(error.localizedDescription)")
Logger.notifications.error("Error scheduling background task: \(error.localizedDescription, privacy: .public)")
}
#endif
...
}
Submitted a bug report: FB16595418
Looking the data over, I think this is bug on our side, as the crash is actually coming from SwiftUI's background task integration, not your own code. It's possible there is a timing issue between your usage and SwiftUI, but that would still mean that SwiftUI changed "something" that altered the timing of activity.
When do you call "BGTaskScheduler.register(forTaskWithIdentifier:using:launchHandler:)"? That's the one behavior you have control over which could be a factor in this crash.
Having said all that, please replicate the issue a few time, collect a sysdiagnose, upload it to your bug, and then let me know here when all of that is done. The sysdiagnose should clarify exactly what's going wrong.
__
Kevin Elliott
DTS Engineer, CoreOS/Hardware
