Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Object-Oriented Swift 2.0 Class Inheritance Creating a Subclass

Posted by Etain Software
Etain Software
5,655 Points

Need help with subclass init

Cant figure out why this is not working, any help would be great.

classes.swift 
class Vehicle {
    let wheels: Int
    let doors: Int

    // Designated initializer
    init(wheels:Int, doors:Int){
      self.wheels = wheels
      self.doors = doors   
    }
}

class Car: Vehicle {
    // A car must default to 4 wheels and 4 doors
    let numberOfSeats: Int = 4
    override init(){
      // call super.init
      super.init(wheels: 4, doors: 4)
    }
}

let someCar = Car(wheels: 3,doors: 3,numberOfSeats)

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi there,

I just wrote another answer for this quiz, so my subclass and initializer are still on my clipboard ... here it is: 

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

  override init(withDoors doors: Int, andWheels wheels: Int){
      self.numberOfSeats = 4
      super.init(withDoors: doors, andWheels: wheels)
  }
}

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

I hope that helps - if you want an explanation after you've read through it, please shout!

Steve.

dansafaeerad
dansafaeerad
3,975 Points

Hi,

I was just wondering why self.numberOfSeats = 4 comes before super.init(withDoors: doors, andWheels: wheels)

Etain Software
Etain Software
5,655 Points
Etain Software
Etain Software
5,655 Points 
class Vehicle {
    var numberOfDoors: Int
    var numberOfWheels: Int    
    init(withDoors doors: Int, andWheels wheels: Int) {
        self.numberOfDoors = doors
        self.numberOfWheels = wheels
    }
}
class Car: Vehicle {
 let numberOfSeats: Int = 4    
    override init(withDoors: Int, andWheels: Int) {
        super.init(withDoors: 4, andWheels: 4)
         }
}
let someCar = Car(withDoors: 12, andWheels: 12 )

got a pass with above code. the external parameter threw me off.

Thanks

Steve Hunter
Steve Hunter
57,712 Points

Cool - glad you got it sorted. :-)