class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let yoho = Notification.Name(rawValue: "yoho")
        let center = NotificationCenter.default
        center.addObserver(self, selector: #selector(foo), 
            name: yoho, object: nil)
        center.post(name: yoho, object: self)
    }
    @objc func foo(_ bar: String) {
        print(bar)
    }
}