Core Data and Asynchronous Fetching on iOS 8

Bart Jacobs explains Apple’s asynchronous fetching solution for Core Data:

“Like batch updates, asynchronous fetching has been on the wishlist of many developers for quite some time. Fetch requests can be complex, taking a non-trivial amount of time to complete. During that time the fetch request blocks the thread it’s running on and, as a result, blocks access to the managed object context executing the fetch request.”