//// Thread sync

////////////////////// CORE DATA ////////////////////////

var mainManagedObjectContext = NSManagedObjectContext(concurrencyType: NSManagedObjectContextConcurrencyType.mainQueueConcurrencyType)
        mainManagedObjectContext.persistentStoreCoordinator = coordinator

var backgroundManagedObjectContext = NSManagedObjectContext(concurrencyType: NSManagedObjectContextConcurrencyType.privateQueueConcurrencyType)
        backgroundManagedObjectContext.persistentStoreCoordinator = coordinator

 NotificationCenter.default.addObserver(self, selector: #selector(AppDelegate.handleMainCoreDataChangeInBackgroundManagedContext(notification:)), name: NSNotification.Name.NSManagedObjectContextDidSave, object: managedObjectContext)

func handleMainCoreDataChangeInBackgroundManagedContext(notification: Notification){
        managedObjectContextBackgroundThread?.mergeChanges(fromContextDidSave: notification)
   }

doSomeChanges()

        do {
            try managedObjectContext.save()
        }catch{
            print(“ERROR: Cound not save Core Data”)
        }
    }

//////////////////// Realm ///////////////////////

// сорян, но для синхронизации Realm код не нужен)