One to many relationship CoreData Swift - ios

Question

Core Data works great for the most part. When I click on name first VC (Items) and performSeque to the second VC (Costs), I can see the costsName and other data. But when I add second name in first VC I can see the same data as in first name.
I'm trying to make a one to many relationship.
I have 2 data models:
import Foundation
import CoreData
#objc(Items)
class Items: NSManagedObject {
#NSManaged var count: NSNumber
#NSManaged var name: String
#NSManaged var cost: NSSet
}
import Foundation
import CoreData
#objc(Costs)
class Costs: NSManagedObject {
#NSManaged var costsDate: NSDate
#NSManaged var costsName: String
#NSManaged var costsValue: NSNumber
#NSManaged var account: Items
}
Here is addAccount's (name of the first VC) save action:
#IBAction func saveButtonPressed(sender: UIBarButtonItem) {
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
var managedObjectContext = appDelegate.managedObjectContext
let entityDescription = NSEntityDescription.entityForName("Items", inManagedObjectContext: managedObjectContext!)
let account = Items(entity: entityDescription!, insertIntoManagedObjectContext: managedObjectContext!)
account.name = cellOneNameTextField.text
if cellTwoCountTextField.text.isEmpty {
} else {
account.count = (cellTwoCountTextField.text).toInt()!
}
// Saving data
appDelegate.saveContext()
var request = NSFetchRequest(entityName: "Items")
var error:NSError? = nil
var results:NSArray = managedObjectContext!.executeFetchRequest(request, error: &error)!
self.navigationController?.popViewControllerAnimated(true)
}
Here is addCost's save action:
#IBAction func saveButtonTapped(sender: UIBarButtonItem) {
// CoreData Access
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
var managedObjectContext = appDelegate.managedObjectContext
let entityDescription = NSEntityDescription.entityForName("Costs", inManagedObjectContext: managedObjectContext!)
let cost = Costs(entity: entityDescription!, insertIntoManagedObjectContext: managedObjectContext!)
cost.costsName = cellThreeNoteTextField.text
cost.costsValue = (cellOnePriceTextField.text).toInt()!
cost.costsDate = datePicker.date
// Saving data
appDelegate.saveContext()
var request = NSFetchRequest(entityName: "Costs")
var error:NSError? = nil
var results:NSArray = managedObjectContext!.executeFetchRequest(request, error: &error)!
for res in results {
println(res)
}
delegate?.refreshTable()
self.navigationController?.popViewControllerAnimated(true)
}

Answer 1

I don't know if you do it somewhere, but your Items should attach a Count object to itself using your cost variable from your Items. Something like :
let account = Items(...)
let cost = Cost(...)
account.cost.addObject(cost)//and changing your var cost:NSSet into var cost:NSMutableSet
//then save Items
(I haven't tried the addObject but you understand the principle)