class Client {
    var apartament: Apartaments
    var name: String
    var dateOfBooking: Date = Date()

    init(apartament: Apartaments, name: String, dateOfBooking: Date) {
        self.apartament = apartament
        self.name = name
        self.dateOfBooking = dateOfBooking
    }
}

class Apartaments {
    weak var client: Client?
    let numberOfRoom: Int
    let floor: Int

    init(numberOfRoom: Int, floor: Int) {
        self.numberOfRoom = numberOfRoom
        self.floor = floor
    }
}

var apartaments = Apartaments(numberOfRoom: 7, floor: 2)
var client = Client(apartament: apartaments, name: "Neuton", dateOfBooking: Date())


apartaments.client = client