UIButtonEventClosure.swift

// The MIT License (MIT)
 
// Copyright (c) 2014 Jan Cássio
 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

import UIKit

typealias DispatchClosure = () -> Dispatch
typealias TargetClosure = () -> ()

@objc class Dispatch: NSObject {
  
  let callback: TargetClosure
  
  init (_ callback: TargetClosure) {
    self.callback = callback
  }
  
  func call() {
    callback()
  }
}

extension UIButton {
  
  /**
    This private struct is used to create pointer refereces to retain Dispatch instance.
    If you want to implement more blocks, don't forget to create a new static var to each one.
  */
  private struct Keys {
    static var TouchUpInsideDispatcher = "TouchUpInsideDispatcher"
  }
  
  /**
    Create an event lister to event type `.TouchUpInside` using closure as target.
  
    Usage:
  
    To listen `.TouchUpInside` events easy, you can simple do this:
  
        var someValue = "Some value"
  
        button.onTouchUpInside({ [unowned button] in
          return Dispatch(){
            console("Label: \(button.titleLabel!.text) Index: \(someValue)")
          }
        })
  
    To remove listener, simple call `onTouchUpInside()` without arguments.
  
    :param: closure A closure block thats return a Dispach instance.
  */
  func onTouchUpInside (closure:DispatchClosure?) -> Void {
    if let _closure = closure {
      let dispatcher = _closure()
      objc_setAssociatedObject(self, &Keys.TouchUpInsideDispatcher, dispatcher, UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
      addTarget(dispatcher, action:"call", forControlEvents:.TouchUpInside)
    }
    else {
      let dispatcher: Dispatch = objc_getAssociatedObject(self, Keys.TouchUpInsideDispatcher) as! Dispatch
      removeTarget(dispatcher, action: "call", forControlEvents: .TouchUpInside)
      objc_setAssociatedObject(self, &Keys.TouchUpInsideDispatcher, nil, UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
    }
    
  }
}