Extensions May not contain Stored properties

Question

Can I implement this in Swift with Extensions without the need to inheritance?. I get this error Extensions May not contain Stored properties

extension UIButton {     @IBInspectable var borderWidth : CGFloat         {         didSet{             layer.borderWidth = borderWidth         }     }  } 

Answer 1

You can override the setter/getter so that it isn't a stored property and just forwards the set/get to the layer.

extension UIButton {     @IBInspectable var borderWidth : CGFloat {         set {             layer.borderWidth = newValue         }          get {             return layer.borderWidth         }     } } 

Answer 2

Extensions cannot add stored properties. From the docs (Computed Properties section):

Note

Extensions can add new computed properties, but they cannot add stored properties, or add property observers to existing properties.

If you have a need for stored properties, you should create a subclass, like so:

class CustomButton : UIButton {     @IBInspectable var borderWidth : CGFloat         {         didSet{             layer.borderWidth = borderWidth         }     }  }