CoreData - fill array with entity attribute in swift

I'm pretty new to Swift/Xcode and I'm faced with a problem of trying to place CoreData attribute values into an array.

The app is a simple shopping list with an entity with 5 attributes:

entity is "Item"

1. image Binary data
2. name String
3. note String
4. qty String
5. status Boolean

The user creates a new shopping item which is displayed in a UITableVIewController (so far I'm fine)

I have to data loading into cells correctly. I also want to display the total quantity(entity "qty") of items in a label.

I can't seem to put each qty into an array so that I can add them together to display them. There seems to be plenty of resources for Objective C but not much out there for swift.

These are what I've been looking at:

Filling an array with core data attributes

CoreData to Array in Swift

Swift: Fetch CoreData as Array

coredata - fetch one attribute into an array

UITableViewController Code:

    let moc = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext

    var frc2 : NSFetchedResultsController = NSFetchedResultsController()
    func fetchRequest2() -> NSFetchRequest {

        let fetchRequest2 = NSFetchRequest(entityName: "Item")
        let sortDescriptor2 = NSSortDescriptor(key: "name",ascending:true)
        fetchRequest2.sortDescriptors = [sortDescriptor2]
        return fetchRequest2
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        //set frc
        frc2 = getFRC()
        frc2.delegate = self

        do {
            try frc2.performFetch()
        } catch {
            print("failed to perform initial fetch request")
            return
        }
    self.tableView.reloadData()
    }

Any help would be greatly appreciated.