Xcode 7 Beta Core Data Error

Trying to save user inputed data into a list to be called by by user at a later point. In the save command (at lines 60 & 67) in Xcode 7 beta, I'm receiving the following command: "Cannot invoke 'save' with an argument list of type '(nil)'" This worked in Xcode 6 and is really the only way I know how to do this, if theres a newer or better way please enlighten me!!

import UIKit
import CoreData
class MainVC: UIViewController {
   
    let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
   
    var nItem : List? = nil
    @IBOutlet weak var entryItem: UITextField!
    @IBOutlet weak var entryNote: UITextField!
    @IBOutlet weak var entryQty: UITextField!
   
   
   
    override func viewDidLoad() {
        super.viewDidLoad()
       
        if nItem != nil {
            entryItem.text = nItem?.item
            entryNote.text = nItem?.note
            entryQty.text = nItem?.qty
           
        }
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        /
    }
    @IBAction func cancelTapped(sender: AnyObject) {
        dismissVC()
    }
   
   
   
    @IBAction func saveTapped(sender: AnyObject) {
       
        if nItem != nil {
            editItem()
        } else {
            newItem()
        }
       
       
        dismissVC()
    }
   
    func dismissVC() {
        navigationController?.popViewControllerAnimated(true)
   
    }
    func newItem() {
        let context = self.context
        let ent = NSEntityDescription.entityForName("List" , inManagedObjectContext: context)
       
        let nItem = List(entity: ent!, insertIntoManagedObjectContext: context)
       
        nItem.item = entryItem.text
        nItem.note = entryNote.text
        nItem.qty = entryQty.text
        context.save(nil)
    }
   
    func editItem() {
        nItem!.item = entryItem.text
        nItem!.note = entryNote.text
        nItem!.qty = entryQty.text
        context.save(nil)
    }
}