KVO implementation swift

KVO.playground

import Foundation

class User: NSObject {
    @objc dynamic var name: String?
    
    init(with name: String) {
        super.init()
        
        self.name = name
    }
}

private var myContext = 0

class UserManager: NSObject {
    var user: User
    
    init(with user: User) {
        self.user = user
        super.init()
        
        self.user.addObserver(self, forKeyPath: #keyPath(User.name), options: .new, context: &myContext)
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        guard context == &myContext else {
            super.observeValue(forKeyPath: keyPath, of: object, change: change, context: &myContext)
            return
        }
        print("alfian", change?[NSKeyValueChangeKey.newKey] ?? "empty")
    }
    
    deinit {
        self.user.removeObserver(self, forKeyPath: #keyPath(User.name), context: &myContext)
    }
}

var newUser = User(with: "Alfian")
var manager = UserManager(with: newUser)

newUser.name = "asd"