Unexpectedly found nil while unwrapping an Optional value with Core Data

Question

So I have been updating my code for Swift 3.0 and when the app is opened I sync with iCloud and execute a fetch request.

However I get the optional error for the following

let appDelegate = UIApplication.shared.delegate as! AppDelegate
     appDelegate.syncWithCompletion { (completed) -> Void in
}

Which executes the following function in the appDelegate

func syncWithCompletion(_ completion:@escaping (_ completed:Bool) -> Void) {

      if !ensemble.isLeeched {
            ensemble.leechPersistentStore { error in
                if error != nil {
                    print("cannot leech \(error!.localizedDescription)")
                    completion(false)
                }
                else {
                    print("leached!!")
                    completion(true)
                }
            }
      }
      else {
            ensemble.merge{ error in
                if error != nil {
                    print("cannot merge \(error!.localizedDescription)")
                    completion(false)
                }
                else {
                    print("merged!!")
                    completion(true)
                    //NSNotificationCenter.defaultCenter().postNotificationName("Updated-DB", object: nil)
                }
           }
      }
}

I am not sure what the optional error is for, Xcode updated the function header when migrating.

UPDATE:

So apparently the following have a nil value

But I am unsure what is causing this since the Swift 3 migration

Put all-exertions breakpoint in xCode, and tell us please where is exactly your error. — Pavel Gatilov, Sep 06 '16 at 13:52
@PavelGatilov I have updated the question, and I am about to double check what else got changed when migrating — A.Roe, Sep 06 '16 at 14:15

score 1 · Answer 1 · answered Sep 06 '16 at 14:33

So I found that the error was because of the didFinishLaunchingWithOptions function in the delegate. The function was not migrated correctly.

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: Any]?) -> Bool {

I created a new project and used the following instead

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

and it worked. This is because the following was not being called therefore my core data stack was not set up

self.setupCoreData()

Why don't you use the (automatically) lazy initialized Core Data Stack as suggested in the Apple template? — vadian, Sep 06 '16 at 14:42

Unexpectedly found nil while unwrapping an Optional value with Core Data

1 Answers1