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 Publisher Subscriber
var player = Player()
let updateScoreSubscriber = Subscribers.Assign(object: player, keyPath: \.score)

// Subscribe
updateScorePublisher.subscribe(updateScoreSubscriber)

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