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iOS Object-Oriented Swift Inheritance Overriding Methods

Van Sanders
Van Sanders
16,087 Points
Posted by Van Sanders
Van Sanders
16,087 Points

Why wont this code pass?

When I set a default value for the roundButton classes incrementBy() method, I get a strange error mentioning that I didn't define a new 'incrementBy()' method (which is clearly not true).

When I omit the default value, it then asks for me to set one... What am I doing wrong?

class Button {
  var width: Double
  var height: Double

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

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

class RoundButton: Button {
  var cornerRadius: Double = 5.0
  override func incrementBy(points: Double = 7.0){
    width += points
    height += points
  }
}

2 Answers

Richard Lu
Richard Lu
20,185 Points
Richard Lu
Richard Lu
20,185 Points

Hey Van,

Everything in your code looks right, but since the overridden method has an optional parameter, you must place an underscore as the parameters external name. 

override func incrementBy(_ points: Double = 7.0){
   width += points
   height += points
}

Hope I've helped. Happy Coding! :)

Richard Lu
Richard Lu
20,185 Points
Richard Lu
Richard Lu
20,185 Points

Hey Van,

I notice that for Swift 1.2, this problem isn't occurring. Have you updated to XCode 7 with Swift 2.0?

Van Sanders
Van Sanders
16,087 Points
Van Sanders
Van Sanders
16,087 Points

Yeah, sorry I was using this forum to help me with this issue, but the same issue is ocurring for me in Xcode 7 with Swift 2.1 - I got the two mixed up in my head.

Your underscore solution did indeed work for my treehouse issue. Thank you!