Monostate Pattern in Swift

main.swift

import Foundation

class Cat { var name = "Kisa" }

let cat = Cat()

class State {
    static var instance = cat
}

class Mono: State {
    var catName: String {
        return State.instance.name
    }
    
    func check() {
        let stateName = State.instance.name
        let thisName  = self.catName
        assert(stateName == thisName)
        
        print(thisName)
    }
}


let monoCat = Mono()
monoCat.check()

State.instance.name = "Pusa"
monoCat.check()

cat.name = "Boris"
monoCat.check()

Mono.instance.name = "Sena"
monoCat.check()