use core data in objective c? code example

Example: core data save

if let contex = (UIApplication.shared.delegate as? AppDelegate)?.persistentContainer.viewContext {}
(UIApplication.shared.delegate as? AppDelegate)?.
// saving context
(UIApplication.shared.delegate as? AppDelegate)?.saveContext()

  if let context = (UIApplication.shared.delegate as? AppDelegate)?.persistentContainer.viewContext {