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iOS Object-Oriented Swift 2.0 Class Inheritance Creating a Subclass

shane reichefeld
PLUS
shane reichefeld
Courses Plus Student 2,232 Points
Posted by shane reichefeld
shane reichefeld
Courses Plus Student 2,232 Points

creating a subclass

Any clarification to how its supposed to be?

classes.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 {
  override init(withDoors doors: Int, andWheels wheels: Int) {
    self.numberOfDoors = doors
    self.numberOfWheels = wheels
    var numberOfSeats: Int = 4
  }
}
let someCar = Car(0,0)

1 Answer

Steven Deutsch
Steven Deutsch
21,046 Points
Steven Deutsch
Steven Deutsch
21,046 Points

Hey Shane Reichefeld,

Good work so far. Let's see if I can clear a few things up for you. First, to create a subclass of vehicle, you need to place a semicolon after the name of the new class declaration, followed by the class it is inheriting from.

class NewClass: ParentClass {
// class body here
}

Next, we just have to add a new property to this Car class, named numberOfSeats, with a default Int value of 4. Since the new properties you're adding all have default values, you don't need to implement another initializer, and you can inherit the initializer of the parent class. Therefore, our setup of this new subclass is relatively simple and complete.

We now need to create an instance of this class, and assign it to the constant someCar. We can do this by calling the initializer of the parent class. Since that initializer was declared using external argument names, withDoors and andWheels, we need to use them when calling the initializer.

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 {
  let numberOfSeats: Int = 4
}

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

Good Luck