swift4 swizzle

Swift4 swizzle

UIViewController-Swizzle.swift


import UIKit

private func swizzle(_ vc: UIViewController.Type) {

​    [ (#selector(vc.viewDidLoad), #selector(vc.sg_viewDidLoad)), ].forEach { original, swizzled in


    let originalMethod = class_getInstanceMethod(vc, original)
    let swizzledMethod = class_getInstanceMethod(vc, swizzled)

    let didAddViewDidLoadMethod = class_addMethod(vc, original, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))
    if didAddViewDidLoadMethod {
        class_replaceMethod(vc, swizzled, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod))
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod)
    }
}



}


private var hasSwizzled = false

extension UIViewController {

​    final public class func doSwizzle() {

​        guard !hasSwizzled else { return }

​        hasSwizzled = true

​        swizzle(self)

​    }


internal func sg_viewDidLoad() {
    print("swizzled -> viewDidLoad:")
    self.sg_viewDidLoad()
}



}


AppDelegate.swift


func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
	// doSwizzle
	UIViewController.doSwizzle()
}