Swift 3.0 & Signals

SignalStation.swift

// The singleton type object

import Foundation
import Signals // -> https://github.com/artman/Signals

class SignalStation
{
  static let shared = SignalStation()
  
  let onValueUpdate = Signal<Int>()
  
  func updateValue(newValue : Int) {
    self.onValueUpdate.fire(newValue)
  }
  
}

View.swift

// subview anywhere in your app

import UIKit

class View : UIView {

  let signalStation = SignalStation.shared

  override init(frame: CGRect) {
    super.init(frame: frame)
    let button : UIButton = UIButton(type: UIButtonType.roundedRect)
    // ...
    button.addTarget(self, action: #selector(updateAction(button:)), for: .touchUpInside)
  }
  
  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
  }
  
  func updateAction(button: UIButton) {
    signalStation.updateValue(newValue: 42)
  }

}

ViewController.swift

// class you want to handle as the value is changed

import UIKit
import Signals // -> https://github.com/artman/Signals

class ViewController : UIViewController {
  
  let signalStation = SignalStation.shared
  
  override func viewDidLoad() {
    super.viewDidLoad()
    signalStation.onValueUpdate.subscribe(on: self) { (value) in
      self.handleNewValue(value)
    }
  }
  
  func handleNewValue(value : Int) {
    print("New Value: \(value)")  // -> 42
  }
  
}