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iOS Object-Oriented Swift 2.0 Class Inheritance Creating a Subclass

Posted by Ray Hiera
Ray Hiera
1,870 Points

Dear Treehouse I find this rather complex and changed the code often It is not clear to me why it won't compile pls

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

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

super.init (withDoors: doors, andWheels: wheels)

} }

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

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: 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)

1 Answer

Reed Carson
Reed Carson
8,306 Points
Reed Carson
Reed Carson
8,306 Points

you are close. I 'm really bad at class initializers, I had to check on it to get right. 

class Car: Vehicle {
    var numberOfSeats: Int = 4

    init(doors: Int, wheels: Int, seats: Int) {
        self.numberOfSeats = seats

        super.init(withDoors: doors, andWheels: wheels)

    }

}

let someCar = Car(doors: 2, wheels: 3, seats: 5)

you want to include all the variables in your override init, and then in the call to the super class init (super.init) you just pass in the values you get from the new init you wrote. The default value needs to be set when the variable is declared, not in the initializer, otherwise you would have no way to change it. The point of initializers is to make sure all constants and variables have a value when the class object is created. Since there is a default value for numberOfSeats, you dont actually need to include it in the initializer, unless you want to be able to set it to something else.

Ray Hiera
Ray Hiera
1,870 Points

Thanks Reed for the advice