👀 Views: 32 💬 Answers: 1 📅 Created: 2025-06-12

core-data ios background-context swift

I've been struggling with this for a few days now and could really use some help. I'm working with a frustrating scenario with Core Data in my iOS 16.2 app. I have a setup where I'm using a background NSManagedObjectContext to perform data imports from a JSON API, but after the import, the changes aren't being saved to the persistent store as expected. The main context is set up correctly and should merge the changes, but I keep getting the behavior `NSManagedObjectContextSaveError` with `behavior Domain=NSCocoaErrorDomain Code=133020` when I try to save. Here’s a snippet of the relevant code: ```swift func importData(with jsonData: Data) { let backgroundContext = persistentContainer.newBackgroundContext() backgroundContext.perform { [weak self] in do { // Assuming `MyEntity` is the Core Data entity let decoder = JSONDecoder() let items = try decoder.decode([MyEntity].self, from: jsonData) for item in items { let entity = MyEntity(context: backgroundContext) entity.property1 = item.property1 entity.property2 = item.property2 // More properties... } try backgroundContext.save() } catch { print("behavior saving background context: \(behavior)") // Handle behavior } } } ``` I’ve also verified that the `persistentContainer` is initialized correctly and that I'm not running into threading issues between contexts. I tried merging the changes into the main context after saving the background context, but it still fails with the same behavior. I looked into potential issues with faulting or validation rules on the entities, but nothing obvious stands out. I even tried changing the merge policy for the main context to `NSMergeByPropertyObjectTrumpMergePolicy`, but that didn’t help either. Is there something specific about using background contexts in iOS 16.2 that I might have overlooked, or is there a common pitfall that could lead to this scenario? Any insights would be greatly appreciated! For context: I'm using Swift on Windows. Any ideas what could be causing this?