@IBDesignable UIButton Extension

Question

I am trying to extend the UIButton class by adding a cornerRadius property which can be changed at the design time without having to build the app. I am using the following extension class:

import UIKit

@IBDesignable
extension UIButton {

    @IBInspectable var cornerRadius :CGFloat {

        get {
            return layer.cornerRadius
        }

        set {

            layer.cornerRadius = newValue
            layer.masksToBounds = newValue > 0
        }
    }

}

But when I make a change of the property cornerRadius in the Storyboard I do not see the change happening live! Am I missing something!

Answer 1

Extensions don't honor the IBDesignable qualifier. Only actual subclasses do. Annoying but true.