快速反射导致任何不可能的零值

我正在尝试使用快速反射来检查对象中的更改,以便我只能将更改的属性发送到服务器.我的一些属性是可选的.为了比较这些值,我需要打开它们,但是,当然,你只能打开实际值,而不是nil值.所以,在比较它们之前,我需要检查其中一个值是否为零.

在我的操场上,我尝试了以下方法：

import UIKit

class myClass
{

    var fieldOne:String?
    var fieldTwo:Int?
    var fieldThree:Float?

}

var oneMyClass = myClass()
oneMyClass.fieldOne = "blah"
oneMyClass.fieldThree = 3.5

var oneOtherClass = myClass()
oneOtherClass.fieldOne = "stuff"
oneOtherClass.fieldTwo = 3

let aMirror = Mirror(reflecting: oneMyClass)
let bMirror = Mirror(reflecting: oneOtherClass)

for thing in aMirror.children
{
    for thing2 in bMirror.children
    {
        if thing.label! == thing2.label!
        {
            print("property: \(thing.label!)")

            print("before: \(thing.value)")
            print("after: \(thing2.value)")
            print("")

            //let myTest = thing.value == nil ? "nil" : "not nil"
        }
    }
}

它会生成以下输出：

property: fieldOne
before: Optional("blah")
after: Optional("stuff")

property: fieldTwo
before: nil
after: Optional(3)

property: fieldThree
before: Optional(3.5)
after: nil

如您所见,预期属性显示为“nil”.但是,如果取消注释let语句,则会收到错误消息：

playground52.swift:37:38: error: value of type 'Any' (aka 'protocol<>') can never be nil, comparison isn't allowed

然而,我们从输出中知道它是零.这怎么可能,我该怎么办呢？

那看起来像某种bug.看那个

let x = childMirror.value == nil ? "Nil" : "Not Nil" //dont compile.

let y = { (value:Any?) in
   return value == nil ? "Nil" : "Not Nil"
}

let z = y(childMirror.value) //compile, but doesn't evaluate.

我猜问题是因为Any可以存储一个Optional,但不能包含一个.试试这个：

func getValue(unknownValue:Any) -> Any {

    let value = Mirror(reflecting: unknownValue)
    if value.displayStyle != .Optional || value.children.count != 0 {
        return "Not Nil"
    } else {
        return "Nil"
    }
}