gistfile1.swift

import Foundation

class EventEmitter {
  var _events : Dictionary<String, Dictionary<Int, (event: Any)->()>?> = [:]
  var _eventsCounter : Int = 0

  func addEventListener(eventName: String, listener: (event: Any) -> ()) -> (Int) {
    _eventsCounter += 1

    var optionalListeners = _events[eventName]
  
    if var listeners = optionalListeners? {
      listeners[_eventsCounter] = listener
      _events[eventName] = listeners

      if listeners.count > 20 {
        println("Potential EventEmitter memory leak: \(listeners.count) listeners subscribed to event \(eventName)")
      }
    }
    else {
      _events[eventName] = [_eventsCounter: listener]
    }

    return _eventsCounter
  }
  
  func removeEventListener(eventName: String, id: Int) {
    var optionalListeners = _events[eventName]
  
    if var listeners = optionalListeners? {
      listeners.removeValueForKey(id)
      _events[eventName] = listeners
    }
  }

  func dispatchEvent(eventName:String, event: Any) {
    var optionalListeners = _events[eventName]
  
    if var listeners = optionalListeners? {
      for (id, listener) in listeners {
        listener(event: event)
      }
    }
  }
}