Ошибка NSManagedObject

Question

Теперь я начал изучать основные данные в iOS. В настоящее время я получаю фатальная ошибка: неожиданно найден nil при развертывании необязательного значения в строке кода ниже. Я читал лекции на youtube и в нескольких других местах и ​​тоже смотрел на их код, но не знал причины этой ошибки. Если кто-то может предоставить мне обзор, это будет действительно полезно. В настоящее время в моем коде я просто назначаю значения из сущности, без выборки.

App Делегат:

lazy var applicationDocumentsDirectory: NSURL = { 
    // The directory the application uses to store the Core Data store file. This code uses a directory named "com.alakh.singh.okejhbs" in the application's documents Application Support directory. 
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask) 
    return urls[urls.count-1] 
}() 

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("ActivityMonitor", withExtension: "momd")! 
    return NSManagedObjectModel(contentsOfURL: modelURL)! 
}() 

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = { 
    // The persistent store coordinator for the application. This implementation creates and returns 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 
    let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel) 
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("SingleViewCoreData.sqlite") 
    var failureReason = "There was an error creating or loading the application's saved data." 
    do { 
     try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil) 
    } catch { 
     // Report any error we got. 
     var dict = [String: AnyObject]() 
     dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" 
     dict[NSLocalizedFailureReasonErrorKey] = failureReason 

     dict[NSUnderlyingErrorKey] = error as NSError 
     let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict) 
     // 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 \(wrappedError), \(wrappedError.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 
    var managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType) 
    managedObjectContext.persistentStoreCoordinator = coordinator 
    return managedObjectContext 
}() 

// MARK: - Core Data Saving support 

func saveContext() { 
    if managedObjectContext.hasChanges { 
     do { 
      try managedObjectContext.save() 
     } catch { 
      // 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. 
      let nserror = error as NSError 
      NSLog("Unresolved error \(nserror), \(nserror.userInfo)") 
      abort() 
     } 
    } 
} 

} 

ViewController:

@IBAction func cofirmLogin(sender: UIButton) { 
    let oct = ((UIApplication.sharedApplication().delegate as? AppDelegate)?.managedObjectContext) 
    var userNameValue = NSEntityDescription.insertNewObjectForEntityForName("LoginInformation", inManagedObjectContext: oct!) as! LoginInformation 
    userNameValue.loginUserName = loginUserName.text! 
    userNameValue.loginPin = Int(loginPin.text!)! 

    userNameValue = loginInfo 
    saveContext(oct!) 
} 

func saveContext (context : NSManagedObjectContext) { 
    if context.hasChanges { 
     do { 
      try context.save() 
     } catch { 
      let nserror = error as NSError 
      NSLog("Unresolved error \(nserror), \(nserror.userInfo)") 
     } 
    } 
} 
} 

Answer 1

Может что-то не работает, как ожидается, с ленивой переменной. Вы можете реорганизовать контекст управляемого объекта, как это.

var managedObjectContext: NSManagedObjectContext { 
    get { 

     if _managedObjectContext == nil { 
      let coordinator = self.persistentStoreCoordinator 
      let moc = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType) 
      moc.persistentStoreCoordinator = coordinator 
      _managedObjectContext = moc 
     } 
     return _managedObjectContext! 
    } 
} 
var _rootContext: NSManagedObjectContext? 

Кроме того, убедитесь, что приложение делегат возвращается, как и ожидалось (возможно разбить это на несколько строк и проверить в отладчике).