Introduction

import UIKit

@objc
protocol ButtonEvent {
    @objc optional func onButtonPress(_ button: UIButton)
}

class ViewController: UIViewController, ButtonEvent {
    @IBOutlet weak var button: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let button = UIButton(frame: CGRect(x: 0, y: 0, width: 100, height: 44))
        button.addTarget(self, action: #selector(ButtonEvent.onButtonPress(_:)), for: .touchUpInside)
        self.view.addSubview(button)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

import Foundation
import UIKit

protocol RemovableTarget {
    func enable();
    func disable();
}

extension UIControl {
    func addEventHandler(event: UIControlEvents, runnable: (control: UIControl) -> Void) -> RemovableTarget {
        
        class Target : RemovableTarget {
            private var event: UIControlEvents
            private weak var control: UIControl?
            private var runnable: (control: UIControl) -> Void
            
            private init(event: UIControlEvents, control: UIControl, runnable: (control: UIControl) -> Void) {
                self.event = event
                self.control = control
                self.runnable = runnable
            }
            
            @objc
            private func run(_ control: UIControl) {
                runnable(control: control)
            }
            
            private func enable() {
                control?.addTarget(self, action: #selector(Target.run(_:)), for: event)
                objc_setAssociatedObject(self, unsafeAddress(of: self), self, .OBJC_ASSOCIATION_RETAIN)
            }
            
            private func disable() {
                control?.removeTarget(self, action: #selector(Target.run(_:)), for: self.event)
                objc_setAssociatedObject(self, unsafeAddress(of: self), nil, .OBJC_ASSOCIATION_ASSIGN)
            }
        }
        
        let target = Target(event: event, control: self, runnable: runnable)
        target.enable()
        return target
    }
}

import Foundation
import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        

        //Create a button.
        let button = UIButton(frame: CGRect(x: 0, y: 0, width: 100, height: 44))
        
        //Add an event action block/listener -- Handles Button Press.
        let target = button.addEventHandler(event: .touchUpInside) { (control) in
            print("Pressed")
        }
        

        self.view.addSubview(button)
        
        //Example of enabling/disabling the listener/event-action-block.
        DispatchQueue.main.after(when: DispatchTime.now() + 5) {
            target.disable() //Disable the listener.
            
            DispatchQueue.main.after(when: DispatchTime.now() + 5) {
                target.enable() //Enable the listener.
            }
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}