swift reflection causes impossible nil value for any

I'm trying to use swift reflection to check for changes in objects so I can send only changed properties up to the server. Some of my properties are optional. To compare those values, I need to unwrap them but, of course, you can ONLY unwrap actual values, not nil values. So, I need to check if one of the values is nil before I compare them.

In my playground, I tried the following:

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"
        }
    }
}

And it generates the following output:

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

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

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

As you can see, the expected properties are displayed as "nil". However, if you uncomment the let statement, you get an error stating:

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

And yet, we know from the output that it IS nil. How can this be and what can I do about it?