首先，

dispatch_once_t

1. 全局变量

2. 静态财产

   struct

   ，

   enum

   或

   class

对于不同的目的，您必须使用不同的实现方式

• 令人毛骨悚然的CocoaTouch类，例如UIViewController;
• 定制的Swift类;
  
  

令人毛骨悚然的CocoaTouch类

例如混写

viewWillAppear(_:)

UIViewController

private let swizzling: (UIViewController.Type) -> () = { viewController in    let originalSelector = #selector(viewController.viewWillAppear(_:))    let swizzledSelector = #selector(viewController.proj_viewWillAppear(animated:))    let originalMethod = class_getInstanceMethod(viewController, originalSelector)    let swizzledMethod = class_getInstanceMethod(viewController, swizzledSelector)    method_exchangeImplementations(originalMethod, swizzledMethod) }extension UIViewController {    open override class func initialize() {        // make sure this isn't a subclass        guard self === UIViewController.self else { return }        swizzling(self)    }    // MARK: - Method Swizzling    func proj_viewWillAppear(animated: Bool) {        self.proj_viewWillAppear(animated: animated)        let viewControllerName = NSStringFromClass(type(of: self))        print("viewWillAppear: (viewControllerName)")    }  }

自定义Swift类

要对Swift类使用方法混乱，必须满足两个要求（有关更多详细信息）：

• 包含要混淆的方法的类必须扩展

  NSObject

• 您想要混淆的方法必须具有

  dynamic

  属性

自定义Swift基类的示例混淆方法

Person

class Person: NSObject {    var name = "Person"    dynamic func foo(_ bar: Bool) {        print("Person.foo")    }}class Programmer: Person {    override func foo(_ bar: Bool) {        super.foo(bar)        print("Programmer.foo")    }}private let swizzling: (Person.Type) -> () = { person in    let originalSelector = #selector(person.foo(_:))    let swizzledSelector = #selector(person.proj_foo(_:))    let originalMethod = class_getInstanceMethod(person, originalSelector)    let swizzledMethod = class_getInstanceMethod(person, swizzledSelector)    method_exchangeImplementations(originalMethod, swizzledMethod)}extension Person {    open override class func initialize() {        // make sure this isn't a subclass        guard self === Person.self else { return }        swizzling(self)    }    // MARK: - Method Swizzling    func proj_foo(_ bar: Bool) {        self.proj_foo(bar)        let className = NSStringFromClass(type(of: self))        print("class: (className)")    }}