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 Inheritance Overriding Methods

Amit Kalra
Amit Kalra
3,078 Points
Posted by Amit Kalra
Amit Kalra
3,078 Points

Override function won't work?

The code is below. I'm doing what I learned in the course and what the question is telling me to do. I even checked w/ Xcode. What am I doing wrong?

Button.swift 
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 : 7){
    width += points
    height += points
  }

}

1 Answer

Petar Popovic
Petar Popovic
Courses Plus Student 23,421 Points

To override a function they need to have same name, get same parameters and return same thing. And your two functions are different, in super class you say points: Double and in sub class you say points: 7. That is why it's not working

Amit Kalra
Amit Kalra
3,078 Points
Amit Kalra
Amit Kalra
3,078 Points

It says I need to put a default value of 7

Petar Popovic
Petar Popovic
Courses Plus Student 23,421 Points

Yes, well you forgot to put underscore. When you want to add value to a parameter like that you need to put underscore first.

This is correct

class RoundButton: Button {
  var cornerRadius: Double = 5.0

  override func incrementBy(_ points: Double = 7.0){
    width += points 
    height += points
  }
Amit Kalra
Amit Kalra
3,078 Points
Amit Kalra
Amit Kalra
3,078 Points

Wow! I actually did put the underscore first and then removed it. It appears I had to put a space after the underscore. I didn't know that. Thanks!

Petar Popovic
Petar Popovic
Courses Plus Student 23,421 Points

You're welcome. I am glad I helped :)