Swift 方法交换

extension UIViewController {
   public class func initializeMethod(){
       
       var originalSelectorArr: [Selector] = Array()
       originalSelectorArr.append(#selector(UIViewController.viewDidAppear(_:)))
       originalSelectorArr.append(#selector(UIViewController.viewDidDisappear(_:)))

       var swizzledSelectorArr: [Selector] = Array()
       swizzledSelectorArr.append(#selector(UIViewController.alertController_viewDidAppear(animated:)))
       swizzledSelectorArr.append(#selector(UIViewController.alertController_viewDidDisappear(animated:)))

       for index in 0 ..< originalSelectorArr.count {
           let originalSelector: Selector = originalSelectorArr[index]
           let swizzledSelector: Selector = swizzledSelectorArr[index]
           let originalMethod = class_getInstanceMethod(self, originalSelector)
           let swizzledMethod = class_getInstanceMethod(self, swizzledSelector)

           //在进行 Swizzling 的时候,需要用 class_addMethod 先进行判断一下原有类中是否有要替换方法的实现
           let didAddMethod: Bool = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod!), method_getTypeEncoding(swizzledMethod!))
           //如果 class_addMethod 返回 yes,说明当前类中没有要替换方法的实现,所以需要在父类中查找,这时候就用到 method_getImplemetation 去获取 class_getInstanceMethod 里面的方法实现,然后再进行 class_replaceMethod 来实现 Swizzing
           if didAddMethod {
               class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod!), method_getTypeEncoding(originalMethod!))
           } else {
               method_exchangeImplementations(originalMethod!, swizzledMethod!)
           }

       }
   }
   
   @objc func alertController_viewDidAppear(animated: Bool) {
       if (ADAlertControllerPriorityQueue.shareInstance().checkShowNextValidity() == true) {
           ADAlertControllerPriorityQueue.shareInstance().showNext()
       }
       self.alertController_viewDidAppear(animated: animated)
   }

   @objc func alertController_viewDidDisappear(animated: Bool) {
       if ADAlertControllerPriorityQueue.shareInstance().currentAlertController?.targetViewController == self, ADAlertControllerPriorityQueue.shareInstance().currentAlertController?.autoHidenWhenTargetViewControllerDisappear == true {
           ADAlertControllerPriorityQueue.shareInstance().currentAlertController?.deleteWhenHiden = false
           ADAlertControllerPriorityQueue.shareInstance().currentAlertController?.hiden()
       }else if(ADAlertControllerPriorityQueue.shareInstance().checkShowNextValidity() == true){
           ADAlertControllerPriorityQueue.shareInstance().showNext()
       }
       self.alertController_viewDidDisappear(animated: animated)
   }
}