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 Value vs Reference Types Final Challenge

Object Oriented Swift Stage 4

Can't figure this out... Below you will find two classes that don't compile. Click on the preview button to see the errors. Look at the errors and fix them one by one until you no longer see any errors.

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

    // Designated initializer
    init(wheels:Int, doors:Int){

    }
}

class Car: Vehicle {
    // A car must default to 4 wheels and 4 doors
    init(){
      // call super.init
    }

2 Answers

William Li
PLUS
William Li
Courses Plus Student 26,868 Points
  • first you need to fill in init(wheels:Int, doors:Int) by setting the object attributes to its corresponding values.
  • then, overwrite the init() in Class Car by using the super.init() method.
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
    init(){
      // call super.init
      super.init(wheels: 4, doors: 4)
    }
}
Steve Dowd
Steve Dowd
1,745 Points

Why is it not necessary to write out the parameters in the init of the subclass Car?