What to choose for working with the database and writing an application?

Question

Swift

Recently I started to delve into Swift. In the examples on Github-e, I noticed such a feature. Some applications pull information from the database through NSFetchedResultsController and sort through NSSortDescriptor, while others do without all this and sort through sort.
Question. Which way is better, faster, why. The code is very different (for me so far). Therefore, I want to determine for myself what to stop at when writing an application. I ask to prompt a difference, "to explain to a teapot".
Thanks!!

Answer 1

It turns out here:
https:
//stackoverflow.com/questions/30933/why-use-nsfetchedresults...
 

Answer 2

Some applications pull information from the database through NSFetchedResultsController and sort through NSSortDescriptor, while others do without all this and sort through sort.

Someone works with CoreData, and someone with Realm. For learning, it's probably better to start with native CoreData. But for the project, at the moment, I would choose Realm.