I want to start learning to use NSAsynchronousFetchRequest by referring to

I even try to execute some simple project from https://github.com/abhishekbedi1432/Core-Data-Asynchronous-Fetching/tree/master which is using NSAsynchronousFetchRequest.

If I do not enable -com.apple.CoreData.ConcurrencyDebug 1, the sample project from github able to perform asynchronous fetch without issue. However, once the -com.apple.CoreData.ConcurrencyDebug 1 is enabled, it will also be getting the same fatal error.

CodePudding user response：

You have to make a new context either a child or a root parent for present Core Data container, like so:

let backgroundContext = persistentContainer.newBackgroundContext()
backgroundContext.parent = persistentContainer.viewContext

Exhaustive explanation of using multiple contexts is here.

CodePudding user response：

For me, the async fetch request works as expected when I provide an estimatedResultCount value to it.