guard let oldModelURL = Bundle.main.url(forResource: "CoreDataTest", withExtension: "momd")?.appendingPathComponent("CoreDataTest.mom"),
      let oldModel = NSManagedObjectModel(contentsOf: oldModelURL)
else { fatalError() }
    
guard let newModelURL = Bundle.main.url(forResource: "CoreDataTest", withExtension: "momd")?.appendingPathComponent("CoreDataTest v2.mom"),
    let newModel = NSManagedObjectModel(contentsOf: newModelURL)
else { fatalError() }
    
let migrator = ManualMigrator(from: oldModel, to: newModel, sourceStoreURL: AppDelegate.current.storeURL, migrationVersion: 1)
migrator.eventDelegate = self
DispatchQueue.global().async {
  migrator.start()
}