Сильная ссылка в Swift

class Employee {
  var name: String
  var colleague: Employee?

  // define initializer
  init(name : String) {
    self.name = name;
  }
}

// create two objects of Employee
var sabby: Employee? = Employee(name: "Sabby")
var cathy: Employee? = Employee(name: "Cathy")
SAMER SAEID