Closure based Selector

DontTrustThisSelector.swift

import Foundation
import PlaygroundSupport
import UIKit

final class Sel {

    static let target = DummyClass.shared

    final class DummyClass {
        static let shared = DummyClass()
        private init() {}
    }

    let action: () -> Void

    @objc func objcAction() { self.action() }

    init(_ action: @escaping () -> Void) {
        self.action = action
    }
}

func Selector(_ action: @escaping () -> Void) -> ObjectiveC.Selector {

    var selectorString = UUID().uuidString
    selectorString.removeAll(where: { $0 == "-" })
    let newSelector = NSSelectorFromString(selectorString)

    let actionMethod = class_getInstanceMethod(
        Sel.self,
        #selector(Sel.objcAction))!
    let typeEncoding = method_getTypeEncoding(actionMethod)!

    let myBlock: @convention(block) () -> Void = { action() }

    let imp = imp_implementationWithBlock(
        unsafeBitCast(myBlock, to: AnyObject.self))

    class_addMethod(
        Sel.DummyClass.self,
        newSelector,
        imp,
        typeEncoding)

    return newSelector
}

let uiButton = UIButton(frame: .init(x: 0, y: 0, width: 200, height: 100))

uiButton.setTitle("Test button", for: .normal)

uiButton.addTarget(
    Sel.target,
    action: Selector {
        print("YEAH")
    },
    for: .touchUpInside)

PlaygroundPage.current.needsIndefiniteExecution = true
PlaygroundPage.current.setLiveView(uiButton)