addObserverExample.swift

let center = NotificationCenter.default
center.addObserver(self, 
                   selector: #selector(onNotificationReceived(_:)), 
                   name: .notificationReceived, 
                   object: nil)

@objc func onNotificationReceived(_ notification:Notification) {
    if let data = notification.userInfo as? [String: Int] {
        // Do something with the data
    }
}