Swift 2，协议扩展& responsesToSelector [英] Swift 2, protocol extensions & respondsToSelector

问题描述

我不确定，它看起来对我来说，这是一种错误或错误的实施与协议扩展在Swift 2.0。

I am not sure, it looks to me that it is some kind of bug or bad implementation with protocol extensions in Swift 2.0.

我有protocolA，protocolB扩展protocolA并在protocolB扩展中实现方法。

I have protocolA, protocolB extending protocolA and implementing methods in protocolB extension.

我已经符合类实例以符合protocolB，但是当通过respondToSelector检查protocolA / B方法时，结果为假。

I have conformed an class instance to conform to protocolB, however when inspected by respondsToSelector for protocolA/B methods the results is false.

import Cocoa
import XCPlayground

protocol ProtocolA : NSObjectProtocol {
  func functionA()
}

protocol ProtocolB : ProtocolA {
  func functionB()
}

extension ProtocolB {
   func functionA() {
     print("Passed functionA")
   }

   func functionB() {
     print("Passed functionB")
   }
}

class TestClass : NSObject, ProtocolB {

    override init () {

    }
}

var instance:TestClass = TestClass()
instance.functionA() // Calls code OK..

if instance.respondsToSelector("functionA") {
    print("Responds to functionA") // **False, never passing here**
}

if instance.respondsToSelector("functionB") {
    print("Responds to functionB") // **False, never passing here**
}

应该报告为错误？

推荐答案

有趣。看起来像一个bug给我。它确实识别类上的函数，但不识别扩展。无论实例具有什么类型。此外，没有扩展代码将不可编译，因为协议方法是非可选的。所以真的看起来像一个错误/功能？以响应选择器实现。

Interesting. Looks like a bug to me. It does recognize functions on a class, but not on extension. No matter what type Instance has. Moreover without an extension code would not be compilable, since protocol methods are non optional. So really looks like a bug/feature? in responds to selector implementation.

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