让我们交换的实现methodOne()，并methodTwo()在我们的TestSwizzling类：
class TestSwizzling : NSObject {
dynamic func methodOne()->Int{
return 1
}
}
extension TestSwizzling {
//在Objective-C中，您需要在load()中执行扫描，
//但是Swift中不允许使用此方法
override class func initialize()
{
struct Inner {
static let i: () = {
let originalSelector = #selector(TestSwizzling.methodOne)
let swizzledSelector = #selector(TestSwizzling.methodTwo)
let originalMethod = class_getInstanceMethod(TestSwizzling.self, originalSelector);
let swizzledMethod = class_getInstanceMethod(TestSwizzling.self, swizzledSelector)
method_exchangeImplementations(originalMethod, swizzledMethod)
}
}
let _ = Inner.i
}
func methodTwo()->Int{
// 混乱后不再是递归调用
return methodTwo()+1
}
}
var c = TestSwizzling()
print(c.methodOne())
print(c.methodTwo())