how to save mixed sort? - swift

Question

From the list in which the words are located, I need to display them in a mixed state.
To do this, I added a shuffle sort field to the entity
func setShuffleWords(id: UUID?) -> [CoreWord]? {
guard let id = id else { return nil }
let requestWords = NSFetchRequest<NSFetchRequestResult>(entityName: "CoreWord")
requestWords.predicate = NSPredicate(format: "ANY dictionary.id == %#", id as CVarArg)
var coreWords: [CoreWord]?
if let result = try? managedContext.fetch(requestWords) as? [CoreWord] {
let words = result.shuffled()
for (index, value) in words.enumerated() {
if value.value(forKey: "shuffle") != nil {
value.setValue(index, forKey: "shuffle")
}
}
coreWords = words
}
save()
return coreWords
}
func getShuffleWords(id: UUID?) -> [CoreWord]? {
guard let id = id else { return nil }
let requestWords = NSFetchRequest<NSFetchRequestResult>(entityName: "CoreWord")
let sort = NSSortDescriptor(key: "shuffle", ascending: true)
requestWords.predicate = NSPredicate(format: "ANY dictionary.id == %#", id as CVarArg)
requestWords.sortDescriptors = [sort]
do {
let result = try managedContext.fetch(requestWords)
return result as? [CoreWord]
} catch let error {
fatalError(error.localizedDescription)
}
}
But, the problem is that if I mix up another list where this word is, then the value is rewritten and it will change its position everywhere.
How to keep mixed order in a specific list?

Answer 1

In this situation you need to replace your many-many relationship with an intermediate entity. Let’s call that entity a Listing. It will represent the listing of a particular word in a particular group, so each Listing should have a to-one relationship to CoreWord and a to-one relationship to CoreGroup. In each case the inverse (which you might call “listings”) should be to-many. The Listing entity should have (at least) one attribute, shuffle, which represents the sequence of a particular word on a particular group.
Life generally gets more complicated, because you have to create and manage these intermediate objects rather than just working the Word and Group objects and their relationships.