import Foundation
import Combine

class Player {
    var score: Int = 0
}

let updateScoreNotificationName = Notification.Name("update_score")

// Create Publisher
let updateScorePublisher = NotificationCenter.Publisher(center: .default,
                                                        name: updateScoreNotificationName,
                                                        object: nil).map { (notification) -> Int in
        return (notification.object as? Int ?? 0)
}

// Create Suscriber Subject
let updateScoreSuscriberSubject = PassthroughSubject<Int, Never>()
var player = Player()
updateScoreSuscriberSubject.assign(to: \.score, on: player)

// Suscribe
updateScorePublisher.subscribe(updateScoreSuscriberSubject)

// Test
NotificationCenter.default.post(name: updateScoreNotificationName, object: 110)
print("Player score is: \(player.score)")