Example of swizzling UIKit classes

UIKit+swizzling.swift

//
//	UIKit+swizzling.swift
//
//	The MIT License (MIT)
//
//	Copyright (c) 2022 Electricwoods LLC, Kaz Yoshikawa.
//
//	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 Foundation
import UIKit
import PlaygroundSupport


fileprivate func swizzleMethod(_ `class`: AnyClass, _ original: Selector, _ swizzled: Selector) {
	if let original = class_getInstanceMethod(`class`, original), let swizzled = class_getInstanceMethod(`class`, swizzled) {
		method_exchangeImplementations(original, swizzled)
	}
	else { print("failed to swizzle: \(`class`.self), '\(original)', '\(swizzled)'") }
}

public extension UIViewController {
	fileprivate static func swizzele_UIViewController() {
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewDidLoad), #selector(UIViewController.viewDidLoad_x))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewWillAppear(_:)), #selector(UIViewController.viewWillAppear_x(_:)))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewDidAppear(_:)), #selector(UIViewController.viewDidAppear_x(_:)))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewWillDisappear(_:)), #selector(UIViewController.viewWillDisappear_x(_:)))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewDidDisappear(_:)), #selector(UIViewController.viewDidDisappear_x(_:)))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewWillLayoutSubviews), #selector(UIViewController.viewWillLayoutSubviews_x))
		swizzleMethod(UIViewController.self, #selector(UIViewController.viewDidLayoutSubviews), #selector(UIViewController.viewDidLayoutSubviews_x))
	}
	@objc private func viewDidLoad_x() {
		print(Self.self, #function)
		self.viewDidLoad_x()
	}
	@objc private func viewWillAppear_x(_ animated: Bool) {
		print(Self.self, #function)
		self.viewWillAppear_x(animated)
	}
	@objc private func viewDidAppear_x(_ animated: Bool) {
		print(Self.self, #function)
		self.viewDidAppear_x(animated)
	}
	@objc private func viewWillDisappear_x(_ animated: Bool) {
		print(Self.self, #function)
		self.viewWillDisappear_x(animated)
	}
	@objc private func viewDidDisappear_x(_ animated: Bool) {
		print(Self.self, #function)
		self.viewDidDisappear_x(animated)
	}
	@objc private func viewWillLayoutSubviews_x() {
		print(Self.self, #function)
		self.viewWillLayoutSubviews_x()
	}
	@objc private func viewDidLayoutSubviews_x() {
		print(Self.self, #function)
		self.viewDidLayoutSubviews_x()
	}
}

public extension UIView {
	fileprivate static func swizzele_UIView() {
		swizzleMethod(UIView.self, #selector(UIView.layoutSubviews), #selector(UIView.layoutSubviews_x))
		swizzleMethod(UIView.self, #selector(UIView.draw(_:)), #selector(UIView.draw_x(_:)))
		swizzleMethod(UIView.self, #selector(UIView.sizeThatFits(_:)), #selector(UIView.sizeThatFits_x(_:)))
	}
	@objc private func layoutSubviews_x() {
		print(Self.self, #function)
		self.layoutSubviews_x()
	}
	@objc private func draw_x(_ rect: CGRect) {
		print(Self.self, #function)
		self.draw_x(rect)
	}
	@objc private func sizeThatFits_x(_ size: CGSize) -> CGSize {
		print(Self.self, #function)
		return self.sizeThatFits_x(size)
	}
}

public extension UIControl {
	fileprivate static func swizzele_UIControl() {
		swizzleMethod(UIControl.self, #selector(UIControl.sendAction(_:to:for:)), #selector(UIControl.sendAction_x(_:to:for:)))
		swizzleMethod(UIControl.self, #selector(UIControl.sendActions(for:)), #selector(UIControl.sendAction_x(for:)))
	}
	@objc private func sendAction_x(_ action: Selector, to target: Any?, for event: UIEvent?) {
		print(Self.self, #function)
		self.sendAction_x(action, to: target, for: event)
	}
	@objc private func sendAction_x(for controlEvents: UIControl.Event) {
		print(Self.self, #function)
		self.sendAction_x(for: controlEvents)
	}
}


UIViewController.swizzele_UIViewController()
UIView.swizzele_UIView()
UIControl.swizzele_UIControl()

class MyViewController : UIViewController {
	lazy var button: UIButton = {
		let button = UIButton(frame: CGRect.zero)
		button.setTitle("Hello", for: .normal)
		button.setTitleColor(UIColor.blue, for: .normal)
		button.layer.borderColor = UIColor.blue.cgColor
		button.layer.borderWidth = 1
		button.layer.cornerRadius = 5
		button.addTarget(self, action: #selector(Self.buttonAction(_:)), for: .touchUpInside)
		return button
	}()
	override func loadView() {
		let view = UIView()
		self.view = view

		view.backgroundColor = .white
		view.addSubview(self.button)
	}
	override func viewWillLayoutSubviews() {
		super.viewWillLayoutSubviews()

		self.button.bounds.size = CGSize(width: 100, height: 40)
		self.button.center = self.view.center
	}
	@objc func buttonAction(_ sender: UIButton) {
		print(Self.self, #function)
	}
}
PlaygroundPage.current.liveView = MyViewController()