CoredataAppDelegateBoilerplate.swift

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

  lazy var persistentContainer: NSPersistentContainer = {
    let container = NSPersistentContainer(name: "DataModel")
      container.loadPersistentStores(completionHandler: { (storeDescription, error) in
          if let error = error as NSError? {
          fatalError("Unresolved error \(error), \(error.userInfo)")
          }
          })
    return container
  }()

  // MARK: - Core Data Saving support

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