swift : AppDelegate and NSManagedObjectContext are nil - ios

Question

I try to create an APP with CoreData and CoreLocation.
CoreLocation works well, but CoreData always give me a fatal error : found nil while unwrapping an Option value every time that i load AppDelegate.
I print appDelegate and NSManagedObjectContext and return nil for both
This is my code into a ViewController
import UIKit
import CoreLocation
import CoreData
class ViewController: UIViewController, CLLocationManagerDelegate {
let locationManager = CLLocationManager()
var appDelegate :AppDelegate?
var context :NSManagedObjectContext?
var entitylUtenti :NSEntityDescription?
func loadCoreData() {
let appDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
let context : NSManagedObjectContext = appDelegate.managedObjectContext!
let entityUtenti = NSEntityDescription.entityForName("Utenti", inManagedObjectContext: context)
if(entitylUtenti == nil) {
println("vuoto")
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
loadCoreData()
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.delegate = self
locationManager.requestWhenInUseAuthorization()
locationManager.startUpdatingLocation()
}
}
In my AppDelegate.swift i insert
lazy var applicationDocumentsDirectory: NSURL = {
// The directory the application uses to store the Core Data store file. This code uses a directory named "xCodingIT.DiarioScolastico" in the application's documents Application Support directory.
let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
return urls[urls.count-1] as! NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
// The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
let modelURL = NSBundle.mainBundle().URLForResource("staffandstock", withExtension: "momd")!
return NSManagedObjectModel(contentsOfURL: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
// The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
// Create the coordinator and store
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("staffandstock.sqlite")
var error: NSError? = nil
var failureReason = "There was an error creating or loading the application's saved data."
if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
coordinator = nil
// Report any error we got.
let dict = NSMutableDictionary()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
dict[NSLocalizedFailureReasonErrorKey] = failureReason
dict[NSUnderlyingErrorKey] = error
error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict as [NSObject : AnyObject])
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext? = {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
let coordinator = self.persistentStoreCoordinator
if coordinator == nil {
return nil
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Core Data Saving support
func saveContext () {
if let moc = self.managedObjectContext {
var error: NSError? = nil
if moc.hasChanges && !moc.save(&error) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
}
}
Anyone have an idea to resolve it ?

Answer 1

By redefining appDelegate & context in the function you're effectively 'shadowing' the instance variables:
func loadCoreData() {
// these two lines
let appDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
let context : NSManagedObjectContext = appDelegate.managedObjectContext!
Remove the let keyword and try again.

Answer 2

I resolve it !!!
I delete my function loadCoreData and insert into func viewDidLoad my appdelegate and my context without let.
I don't know why if i remove let from loadCoreData nothing change ... but now it works !!!