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iOS Object-Oriented Swift Class Inheritance Creating a Subclass

Posted by Zeyad Salah Elhennawi
Zeyad Salah Elhennawi
1,586 Points

how to initialise instances into an inherited class?

If I have a class and make a new one which is an inherited one and added some instance. should I initialise its constants and the inherited ones?

objects.swift 
class Vehicle {
  var numberOfDoors: Int
  var numberOfWheels: Int

  init(withDoors doors: Int, andWheels wheels: Int) {
      self.numberOfDoors = doors
      self.numberOfWheels = wheels
  }
}


// Enter your code below
class Car: Vehicle {
    var numberOfSeats: Int
    init (numberOfSeats: Int){
        self.numberOfSeats = numberOfSeats
    }
}
let someCar = Car(numberOfSeats: 4)

1 Answer

David Papandrew
David Papandrew
8,386 Points
David Papandrew
David Papandrew
8,386 Points

Lazy way to do it (what I would do):

// Enter your code below
class Car: Vehicle {
    var numberOfSeats: Int = 4
}

let someCar = Car(withDoors: 4, andWheels: 4)

Since you set a default value for numberOfSeats, no need to create new initializer. New instance of this subclass will use the default property and all you have to do is create new instance with the parent class initializer.

If you must create a new initializer, this is how it would look:

// Enter your code below
class Car: Vehicle {
    var numberOfSeats: Int = 4

    init(withDoors doors: Int, andWheels wheels: Int, numberOfSeats: Int) {
        self.numberOfSeats = numberOfSeats
        super.init(withDoors: doors, andWheels: wheels)
    }
}

let someCar = Car(withDoors: 4, andWheels: 4, numberOfSeats: 4)