Can't connect IBAction in Xcode

Question

When I drag from a button on the storyboard to my view controller Swift file, I only get the option to insert an Outlet or Outlet Collection.

Similarly, if I create the

Answer 1

If extension is causing the problem, then instead of directly extending UIButton, user typealias e.g, create extension of CustomButton instead of UIButton

typealias CustomButton = UIButton
extension CustomButton { }