我该如何以模态呈现viewController。是ios中的新手，并且正在使用swift4我尝试了
let userVC = mainStoryboard.instantiateViewController(withIdentifier:
"menuC") as! MenuController
userVC.modalPresentationStyle = UIModalPresentationStyle.overCurrentContext
userVC.navigationController?.modalPresentationStyle =
UIModalPresentationStyle.overCurrentContext
present(userVC, animated: true, completion: nil)