I have encountered an issue that when using a ModelActor to sync data in the background, the app will crash if one of the operations is to remove a PersistentModel from the context.
This is running on the latest beta of Xcode 16 with visionOS 1.2 as target and in Swift 6 language mode.
The code is being executed in a ModelActor.
The error is first thrown by: #5 0x00000001c3223280 in PersistentModel.getValue<τ_0_0>(forKey:) ()
Thread 1: Fatal error: Context is missing for Optional(SwiftData.PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: x-coredata://97AA86BC-475D-4509-9004-D1182ABA1922/Reminder/p303), implementation: SwiftData.PersistentIdentifierImplementation))
func globalSync() async {
await fetchAndSyncFolders()
let result = await fetchReminders()
switch result {
case .success(let ekReminders):
var localReminders = (try? await fetch(FetchDescriptor<Reminder>())) ?? []
// Handle local reminders with nil ekReminderID by creating new EKReminders for them
for reminder in localReminders {
if reminder.ekReminderID == nil {
await self.createEkReminder(reminder: reminder)
}
}
// Re-fetch local reminders to include newly created EKReminderIDs
localReminders = (try? await fetch(FetchDescriptor<Reminder>())) ?? []
var localReminderDict = [String: Reminder]()
for reminder in localReminders {
if let ekReminderID = reminder.ekReminderID {
if let existingReminder = localReminderDict[ekReminderID] {
self.delete(model: existingReminder)
} else {
localReminderDict[ekReminderID] = reminder
}
}
}
let ekReminderDict = createReminderLookup(byID: ekReminders)
await self.syncReminders(localReminders: Array(localReminderDict.values), localReminderDict: localReminderDict, ekReminderDict: ekReminderDict)
// Merge duplicates
await self.mergeDuplicates(localReminders: localReminders)
save()
case .failure(let error):
print("Failed to fetch reminders: \(error.localizedDescription)")
}
}
Thread 1: Fatal error: Context is missing for Optional(SwiftData.PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: x-coredata://97AA86BC-475D-4509-9004-D1182ABA1922/Reminder/p303), implementation: SwiftData.PersistentIdentifierImplementation))
I am pretty sure that simply deleting a model object using (or not) a model actor (ModelActor) doesn't trigger the mentioned crash.
This error indicates that your model object doesn't have a valid model context, which can happen when you hold a SwiftData model object in a SwiftUI view and continue to access the object (as the view is updated) after it was deleted.
If that is not your case, please share a minimal project, with detailed steps, to reproduce the issue. I'll be interested in taking a look.
Best,
——
Ziqiao Chen
Worldwide Developer Relations.
