CODEWITHSUNDEEP
swiftcore-datansfetchrequestnsorderedset
Filip Krawczyk
Filip Krawczyk

Reputation: 105

What sort descriptor will keep the order of NSOrderedSet when using FetchRequest in SwiftUI

I have 2 entities in CoreData. Deck and Flashcard. Deck has an ordered to-many relationship with Flashcard. This means that Deck contains property flashcards: NSOrderedSet containing the Flashcards.

In a DeckView I try to show all Flashcards from a certain Deck in a user-specified order. For that I use FetchRequest.

static func fetchInDeck(deck: Deck) -> NSFetchRequest<Flashcard> {
    let request = Flashcard.fetchRequest()
    request.predicate = NSPredicate(format: "deck == %@", deck)
    request.sortDescriptors = []
    return request
}

The flashcards maintain order until I start adding items, new items get added in seemingly random places, but after restarting the app they go where they should. (e.g. after adding 10 items the order was [3 5 7 9 10 8 6 4 2 1], and after restart [10 9 8 7 6 5 4 3 2 1]) For adding I used a method generated automatically by Xcode.

let newFlashcard = Flashcard(context: context)
insertIntoFlashcards(newFlashcard, at: 0)

Is there a sort descriptor that will cause those items to stay in order? If not is there another way to maintain the order?

Upvotes: 1

Views: 102

Answers (0)

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