Initialization of classes with a constructor in Swift

let nokiaPhone = Phone(model: "Nokia 6610");

let kim = Employee(firstName: "Victorya",
    lastName: "Kim",
    personalPhone: Phone(model: "iPhone 5"))

class Phone {
    var model: String
    
    init (model: String) {
        self.model = model
    }
}

class Employee {
    var firstName: String
    var lastName: String
    var personalPhone: Phone
    
    init (firstName: String, lastName: String, personalPhone: Phone) {
        self.firstName = firstName
        self.lastName = lastName
        self.personalPhone = personalPhone
    }
}