ActionTrampoline - Use Swift blocks for your Control actions

ActionTrampoline.swift

//
//  ActionTrampoline.swift
//  Swift 3
//
//  Created by Jason Jobe on 3/17/16.
//  Copyright © 2016 WildThink. All rights reserved.
//
//  https://gist.githubusercontent.com/wildthink/677308084ab364044c76/raw/f713efca9ec6ca9b56c4405bd82ae33b1db98ec7/ActionTrampoline.swift
//
// Kudos (again) to Mike Ash!
// https://www.mikeash.com/pyblog/friday-qa-2015-12-25-swifty-targetaction.html
//
import Foundation

import Foundation


#if os(iOS)
    import UIKit
    
    protocol UIControlActionFunctionProtocol {}
    
    class ActionTrampoline<T>: NSObject
    {
        var action: (T) -> Void
        
        init(action: @escaping (T) -> Void) {
            self.action = action
        }
        
        @objc func performAction(sender: UIControl) {
            action(sender as! T)
        }
    }
    
let NSControlActionFunctionProtocolAssociatedObjectKey = UnsafeMutablePointer<Int8>.allocate(capacity: 1)
    
    extension UIControlActionFunctionProtocol where Self: UIControl
    {
        func addAction(events: UIControlEvents, _ action: @escaping (Self) -> Void) {
            let trampoline = ActionTrampoline(action: action)
            let call = #selector(trampoline.performAction(sender:))
            self.addTarget(trampoline, action: call, for: events)
            objc_setAssociatedObject(self, NSControlActionFunctionProtocolAssociatedObjectKey, trampoline, .OBJC_ASSOCIATION_RETAIN)
        }
        
        func removeActionBlock() {
            objc_setAssociatedObject(self, NSControlActionFunctionProtocolAssociatedObjectKey, nil,
                                     .OBJC_ASSOCIATION_RETAIN)
        }
        

        func setup(setup: (Self) -> Void) -> Self {
            setup(self)
            return self
        }
    }
    
    extension UIControl: UIControlActionFunctionProtocol {}
    
#else
    
    import Cocoa
    
    protocol NSControlActionFunctionProtocol {}
    
    class ActionTrampoline<T>: NSObject
    {
        var action: (T) -> Void
        
        init(action: @escaping (T) -> Void) {
            self.action = action
        }
        
        @objc func performAction(sender: NSControl) {
            action(sender as! T)
        }
    }
    
let NSControlActionFunctionProtocolAssociatedObjectKey = UnsafeMutablePointer<Int8>.allocate(capacity: 1)
    
    extension NSControlActionFunctionProtocol where Self: NSControl
    {
        var actionBlock: ((Self) -> Void)? {
            set {
                guard let action = newValue else {
                    objc_setAssociatedObject(self, NSControlActionFunctionProtocolAssociatedObjectKey, nil,
                                             .OBJC_ASSOCIATION_RETAIN)
                    return
                }
                let trampoline = ActionTrampoline(action: action)
                self.target = trampoline
                self.action = #selector(trampoline.performAction(sender:))
                objc_setAssociatedObject(self, NSControlActionFunctionProtocolAssociatedObjectKey, trampoline, .OBJC_ASSOCIATION_RETAIN)
            }
            get {
                guard let trampoline: ActionTrampoline =
                    objc_getAssociatedObject(self, NSControlActionFunctionProtocolAssociatedObjectKey) as? ActionTrampoline<Self> else { return nil }
                return trampoline.action
            }
        }
        
        func setup(setup: (Self) -> Void) -> Self {
            setup(self)
            return self
        }
    }
    
    extension NSControl: NSControlActionFunctionProtocol {}
    
#endif


// Demo

#if os(iOS)
var button = UIButton(frame: CGRect(x: 0, y: 0, width: 64, height: 32))
    button.addAction(events: .allEditingEvents) {
        Swift.print ($0.title(for: .highlighted) ?? "uhoh")
    }
    
    button.sendActions(for: .allEditingEvents)
#else

var button = NSButton(frame: NSRect(x: 0, y: 0, width: 64, height: 32))
button.setAction() {
    Swift.print ($0.title)
}

button.actionBlock = {
    Swift.print ($0.title)
}

let button2 = NSButton(frame: NSRect(x: 0, y: 0, width: 64, height: 32)).setup { me in
    me.setAction () {
        Swift.print ($0.title)
    }
}

print (button.actionBlock)

button.performClick(nil)
button.actionBlock?(button)
#endif