Question

I’m creating my managed object context with NSPrivateQueueConcurrencyType concurrency type.

Also I’m using performBlock: selector to execute operations in background. So If I’m fetching some objects in background (in performBlock:), is it safe to use resulting managed objects in main thread?

Answer 1

As a general rule, no it is not safe to share NSManagedObject instances across threads no matter what concurrency type you are using.

However there is a library you can use to make your context(s) and object instances thread-safe. With that you can pretty much ignore all the nonsense about ensuring thread isolation between contexts and focus your efforts on the things that matter, like building out the actual functionality of your app.