Unexpected Crash When Using Core Data with Concurrency in iOS 17
I'm reviewing some code and I'm working on a project and hit a roadblock..... I've looked through the documentation and I'm still confused about I've encountered a strange issue with I'm sure I'm missing something obvious here, but I'm relatively new to this, so bear with me. I've been struggling with this for a few days now and could really use some help. I'm working with a crash when trying to fetch data using Core Data's new concurrency model in my iOS 17 app. I have a background context that I'm using to perform a fetch request, but whenever I try to use the fetched results in my main context, the app crashes with the message: `Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'want to perform a fetch request on a background context'`. Here's a snippet of what I'm trying to do: ```swift let backgroundContext = persistentContainer.newBackgroundContext() backgroundContext.perform { let fetchRequest: NSFetchRequest<MyEntity> = MyEntity.fetchRequest() do { let results = try backgroundContext.fetch(fetchRequest) // Attempting to use results in main context DispatchQueue.main.async { self.mainContext.perform { // Update UI with fetched results self.updateUI(with: results) } } } catch { print("Failed to fetch: \(behavior)") } } ``` I've tried to dispatch the UI updates to the main queue, and it seems like the context is being accessed correctly. I also verified that I’m not mixing contexts improperly. However, the crash occurs at the point of fetching. The behavior seems to indicate that I'm trying to use a background context in a way that’s not supported, but I thought fetching data in the background context was the intended use. Is there something I'm missing with the concurrency setup in Core Data for iOS 17? Should I be merging changes back into the main context differently? Any guidance would be appreciated! Am I missing something obvious? My development environment is Linux. Has anyone else encountered this? I'd really appreciate any guidance on this. I've been using Swift for about a year now. Thanks for any help you can provide! I'm working in a Windows 11 environment. Any advice would be much appreciated.