How to switch between different CoreData Entities in NSFetchedResultsController?

I am using a CoreData in my project. It has 2 separate Entities : Currency and Currency2 . The entities have identical attributes, but store a different data which populates a tableView . And user can choose which data he wants to see in the tableView by picking the option in app settings (I can store his choice by saving it in UserDefaults ).

The problem here is how can I populate the tableView with a different Entity data? I can't just change a name like in string literal in here from Currency to Currency2 :

private var fetchedResultsController: NSFetchedResultsController<Currency>!

It will just give me an error. So I assume I should create one more fetchedResultsController...:

private var fetchedResultsController: NSFetchedResultsController<Currency2>!

But then I should double all the below code since I need to switch between them. And what If in future I will need to switch between 3 or 4 different Entities ?

How can I make the code reusable and at the same time receive a desired switch result with NSFetchedResultsController ?

For now my NSFetchedResultsController set up as follows:

class CurrencyViewController: UIViewController {

  private var fetchedResultsController: NSFetchedResultsController<Currency>!

   override func viewWillAppear(_ animated: Bool) {

    //MARK: - TableView DataSource Methods

     func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
            return fetchedResultsController.sections![section].numberOfObjects

     func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
           let cell = tableView.dequeueReusableCell(withIdentifier: "currencyCell", for: indexPath) as! CurrencyTableViewCell
           let currency = fetchedResultsController.object(at: indexPath)
           cell.shortName.text = currency.shortName
           cell.fullName.text = currency.fullName

           return cell

   //MARK: - NSFetchedResultsController Setup & Delegates

      func setupFetchedResultsController(with searchPredicate: NSPredicate? = nil) {
           let predicate = NSPredicate(format: "isForCurrencyScreen == YES")
           var sortDescriptor: NSSortDescriptor {
            if pickedSection == "По имени" {
                return NSSortDescriptor(key: "fullName", ascending: sortingOrder)
            } else {
                return NSSortDescriptor(key: "shortName", ascending: sortingOrder)

          fetchedResultsController = coreDataManager.createCurrencyFetchedResultsController(with: predicate, and: sortDescriptor)
          fetchedResultsController.delegate = self
          try? fetchedResultsController.performFetch()

      func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {

      func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {

And this is also my coreDataManager.createCurrencyFetchedResultsController method:

  private let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

  func createCurrencyFetchedResultsController(with predicate: NSPredicate? = nil, and sortDescriptor: NSSortDescriptor? = nil) -> NSFetchedResultsController<Currency> {
        let request: NSFetchRequest<Currency> = Currency.fetchRequest()
        let baseSortDescriptor = NSSortDescriptor(key: "shortName", ascending: true)
        request.predicate = predicate
        return NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)

The entities have identical attributes, but store a different data

Why don’t you use a single currency entity with a isCurrency2 boolean attribute which you can use to filter your data?

Hi! Thank you for the reply. I consider about the option you advise but decided this is not suitable for my case. But maybe I was wrong. Let me clarify:

In my app I have 2 different currency data sources: Forex data with 160 currencies and local bank with 30 currencies.

So I make a separate networking and after JSON parsing store local bank 30 entries under Currency Entity.

Now I want to add a second data source Forex and I also want to store differently its actualValue, yesterdayValue attributes plus also some of the attributes have different data for the Forex and LocalBank despite the same attribute name:

Later I use this value attributes in a ConverterViewController, so I store also attribute isForConverter which represents the particular entry was picked by user to convert.

That's is why I decided that to store it in separate Entities is a good idea. Then after first data parsing my user can switch between the data without an internet connection.

What do you think?