Swift msethod-swizzle

发表于 |

Swift 当中也可以使用 method swizzle 在运行时进行方法交换，通常在某种情况下很有用，比如统计页面 Button 点击了多少次，可以扩展 UIButton 来实现，

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extension UIButton{
  class func swipButtonAction(){
    struct T {
      static var swizzle: Bool = {
        let cls: AnyClass = UIButton.self

        let originalSelector = #selector(UIButton.sendAction(_:to:for:))
        let swizzleSelector = #selector(UIButton.swizzle_sendAction(action:to:forEvent:))

        let origin_method = class_getInstanceMethod(cls, originalSelector)
        let swizzle_method = class_getInstanceMethod(cls, swizzleSelector)

        // 交换两个方法实现
        method_exchangeImplementations(origin_method, swizzle_method)

        return false
      }()
    }

    _ = T.swizzle
  }

  // 定义要交换的函数
  public  func swizzle_sendAction(action: Selector,
                                  to: AnyClass!,
                                  forEvent: UIEvent!){
    // 累加器
    struct button_tap_count{
      static var count = 0
    }

    button_tap_count.count += 1
    print(button_tap_count.count)
    // 看似好像调用了自己构成死循环,但是 我们其实已经将两个方法名的实现进行了调换 所以 其实我们调用的是 方法sendAction:to:forEvent 的实现 这样就可以在不破环原先方法结构的基础上进行交换实现
    swizzle_sendAction(action: action, to: to, forEvent: forEvent)
  }
}

参考

swift swizzle