remove duplicates in coredata and automatically update in tableview in swift

main.swift
// create the fetch request
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "EntityName")
fetchRequest.resultType = .dictionaryResultType
fetchRequest.propertiesToFetch = ["attributeName"]
fetchRequest.returnsDistinctResults = true
fetchRequest.sortDescriptors = [NSSortDescriptor(key: "attributeName", ascending: true)]

// execute the fetch request
let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
fetchedResultsController.delegate = self
do {
    try fetchedResultsController.performFetch()
} catch {
    print(error)
}

// implement the NSFetchedResultsControllerDelegate
extension ViewController: NSFetchedResultsControllerDelegate {
    func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        tableView.reloadData()
    }
}

// display the results in the tableview
override func numberOfSections(in tableView: UITableView) -> Int {
    return fetchedResultsController.sections?.count ?? 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return fetchedResultsController.sections?[section].numberOfObjects ?? 0
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
    let object = fetchedResultsController.object(at: indexPath) as! NSManagedObject
    cell.textLabel?.text = object.value(forKey: "attributeName") as? String
    return cell
}
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