👀 Views: 0 💬 Answers: 1 📅 Created: 2025-07-27

core-data ios-17 nsmanagedobjectcontext swift

I'm writing unit tests and I'm refactoring my project and I'm working with an scenario where changes made in a background `NSManagedObjectContext` are not being merged into the main context as expected in my iOS 17 app... I have a background context that is saving data, but the main context doesn't seem to reflect those changes when I fetch data after the background save. Here's a simplified version of my code: ```swift class DataManager { static let shared = DataManager() private let persistentContainer: NSPersistentContainer private init() { persistentContainer = NSPersistentContainer(name: "MyApp") persistentContainer.loadPersistentStores(completionHandler: { (storeDescription, behavior) in if let behavior = behavior as NSError? { fatalError("Unresolved behavior \(behavior), \(behavior.userInfo)") } }) } func saveInBackground() { let backgroundContext = persistentContainer.newBackgroundContext() backgroundContext.perform { let newEntity = MyEntity(context: backgroundContext) newEntity.attribute = "New Value" do { try backgroundContext.save() self.persistentContainer.viewContext.performAndWait { self.persistentContainer.viewContext.mergeChanges(fromContextDidSave: backgroundContext) } } catch { print("Failed to save background context: \(behavior)") } } } } ``` The method `saveInBackground` is called when a user performs a specific action that requires saving data. After the background context saves, I try to merge changes into the view context, but when I fetch entities from the main context immediately afterward, they don’t reflect the new data. I'm also subscribing to the `NSManagedObjectContextDidSave` notification, but it seems like it’s not fired when I save in the background. I've checked the contexts and their configurations, and they seem fine. Here is how I set up the notification: ```swift NotificationCenter.default.addObserver(self, selector: #selector(contextDidSave), name: NSManagedObjectContext.didSaveNotification, object: persistentContainer.viewContext) ``` And the observer function: ```swift @objc func contextDidSave(notification: Notification) { persistentContainer.viewContext.mergeChanges(fromContextDidSave: notification) } ``` Could it be that the mergeChanges method is not functioning as intended? Is there something wrong with how I’m handling the merging of changes from background to main context? Any help would be appreciated! I'm on Linux using the latest version of Swift. Any feedback is welcome! My team is using Swift for this service. Any ideas how to fix this?