Why not using `performBlock` and `performBlockAndWait`?

[hadiidbouk]

From Apple Documentation

The NSPrivateQueueConcurrencyType configuration creates its own queue upon initialization and can be used only on that queue. Because the queue is private and internal to the NSManagedObjectContext instance, it can only be accessed through the performBlock: and the performBlockAndWait: methods.

Why you are not using these two methods in your code?