使用反射调用方法 [英] Calling Method using reflection

问题描述

据我所知，Swift 中的反射目前还不太可用.为了性能，我目前正在将 Objective-c 代码转换为 swift(我注意到了相当大的差异).

As I understand reflection in Swift is poorly available as of yet. I am currently in the process of converting objective-c code to swift for the sake of performance (I have noticed a considerable difference).

现在我需要的是一种使用反射调用方法的方法.需要调用该方法的对象扩展 NSObject 以允许使用以下代码解析该类；

Now what I need is a way to call a Method using reflection. The object the method needs to be called upon extends NSObject to enable the class to be resolved using the following code;

let clazz = NSClassFromString("MyProject.DynamicClass") as NSObject.Type; 
let clazzInstance = clazz() as! NSObject;

我可以使用以下代码检索参数的数量和对该方法的引用；

I am able to retrieve a the number of argument and a reference to the method using the following code;

let selectorMethod = Selector("myCustomMethod:");

let numberOfArguments : UInt32 = method_getNumberOfArguments(selectorMethod);
let referenceToMethod : Method = class_getInstanceMethod(clazz, selector!);

但是我如何使用/调用referenceToMethod?

But how do I use/call the referenceToMethod?

附加
我也试过调用 performSelector 但这已被 Swift 2 完全删除.我也想阻止使用任何 @objc 属性/注释.

推荐答案

如果你正在寻找一种完全 Swifty 的反射方式，那么拥有需要调用的方法的对象根本不需要是 NSObject，相反，它只需要一个必需的初始化程序.看看下面的例子:

If you are looking for a completely Swifty way of reflection, the object that has the method that needs to be called does not need to be a NSObject at all, instead all it need is a required initializer. Have a look at below example :

class A{

    required init(){

    }
    func printSomething(s:String){

        println(s)
    }
}

// initializing object dynamically from class
let clazz = NSClassFromString("MyProject.A") as! A.Type   
let clazzInstance = clazz()

// getting and calling its methods in Swifty way    
let method = clazzInstance.printSomething 
method("something")

使用它的好处在于您根本不需要使用强制转换，并且调用带有错误参数的方法会触发编译时错误

The advantage of using this stands on fact that you wont need to use casting at all and also calling method with wrong arguments would trigger a compile time error

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