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iOS Object-Oriented Swift Inheritance Inheritance and Initializers

Having trouble with this question. Any help would be great!

Once again we are working with the RoundButton class and started to add a designated initializer to it. However, there's something wrong with it. Can you figure out how to fix it and make it work?

Button.swift
class Button {
  var width: Double
  var height: Double

  init(width:Double, height:Double){
    self.width = width
    self.height = height
  }

  func scaleBy(points: Double){
    width += points
    height += points
  }
}

class RoundButton: Button {
  var cornerRadius: Double = 5.0

  init(width:Double,height:Double,cornerRadius:Double){
    self.cornerRadius = cornerRadius
  }  
}

1 Answer

Jason Anders
MOD
Jason Anders
Treehouse Moderator 145,858 Points

Hey Paul.

Because roundButton inherits from Button, you also need to include a super.init for the inherited values.

class RoundButton: Button {
  var cornerRadius: Double = 5.0

  init(width:Double,height:Double,cornerRadius:Double){
    self.cornerRadius = cornerRadius
    super.init(width: width, height: height)
  }  
}

Because you are using properties from the Super Class, they must also be initialized, by using super.init. Amit goes over this in this video starting just after the 3 minute mark.

Keep Coding! :)