https://www.jianshu.com/p/a6b675f4d073
+(void)load 方法已经失效
swift3.0 中的 initialize 也失效
网络收集来的代码，做记录
extension UIViewController {
public class func initializeMethod() {
let originalSelector = #selector(UIViewController.viewDidAppear(_:))
let swizzledSelector = #selector(UIViewController.myMethod(animated:))
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 myMethod(animated: Bool) {
self.myMethod(animated: animated)
}