Optional Any? equals to nil - swift

Question

I have:
let value: Any? = myObject[keyPath: myParamKeyPath]
where myParamKeyPath refers to a String?.
Then, when myParam is supposed to be nil, I have:
value == nil returns false
(value as? String?) == nil returns true
Is it possible to check if value equals nil without having to cast it to a String? in the first place? Something like comparing it to NSNull maybe?
Also, I can't change the value type to String? directly as it is also used for other type in my code.
EDIT:
(value as? String?) == nil returns true is irrelevant indeed.
But I can still go print my value pointed by the keypath and it will actually be nil. So I still don't get why value == nil returns false when Im expecting it to be true...
EDIT2 with more code:
let setting = appSettings.settings[indexPath.row]
let value = appSettings[keyPath: setting.keyPath]
let fontAwesome: FontAwesome
switch setting.keyPath {
case \PrinterSettings.printableImageIDs:
fontAwesome = blablabla
case \WeatherSettings.lockscreenImageIDs:
fontAwesome = blablabla
default:
if let value = value as? FakeButtonPlacementSubSettings {
fontAwesome = blablabla
} else {
fontAwesome = value != nil ? .checkSquareO : .squareO
}
}
I am expecting to get fontAwesomeIcon = .squareO but I am getting checkSquareO when the value pointed by myObject[keyPath: myParamKeyPath] is String? (it does the same for another value which is a Bool? later on).
I must be missing something somewhere...
EDIT 3 screenshot:
EDIT 4 more clarification of what I'm trying to do here:
First, thank you again for your help if you get there.
Here are 2 photos about my project current design:
I am using with KVO in my project. I was previously using the objective-c string #keyPath for this. It was working great, but almost all my model had to be converted in #objc. So my current goal here is to remove it and switch to the new Swift 4 keypath system.
To resume: I have a user class containing lot of settings (more than on the screenshot) which can be of several type (and some custom types also).
On the other hand, I have created around 10 "setting editor view controllers": one by type of settings. I would like to use the same setting editor VC to edit each one of the same type of settings.
For example, if the setting to edit is a boolean, I would like to use the "boolean editor VC" and get my selected setting edited by the user's new choice. This is why I am using KVO system. I'm not willing to keep it if you guys have a better solution for this. It would then also get rid of my Any? == nil issue.

Answer 1

How about the following?
struct S {
let x: String?
}
let v1: Any? = S(x: "abc")[keyPath: \S.x]
print(v1 is String? && v1 == nil) // false
let v2: Any? = S(x: nil)[keyPath: \S.x]
print(v2 is String? && v2 == nil) // true

Answer 2

The issue is that your code is assuming the value is String?, whereas it is really String??. I believe this stems from the use of AnyKeyPath:
struct Foo {
let bar: String?
}
let foo = Foo(bar: "baz")
let keyPath: AnyKeyPath = \Foo.bar
print(foo[keyPath: keyPath]) // Optional(Optional("baz"))
let keyPath2 = \Foo.bar
print(foo[keyPath: keyPath2]) // Optional("baz")
I wonder if there is some way to adapt your code to use KeyPath<T, String?> pattern, so that, as you say, your myParamKeyPath really does explicitly refer to a String?, .e.g.:
let foo = Foo(bar: "baz")
let keyPath = \Foo.bar
func keyPathExperiment(object: Any, keyPath: AnyKeyPath) {
print(object[keyPath: keyPath])
}
func keyPathExperiment2<T>(object: T, keyPath: KeyPath<T, String?>) {
print(object[keyPath: keyPath])
}
keyPathExperiment(object: foo, keyPath: keyPath) // Sigh: Optional(Optional("baz"))
keyPathExperiment2(object: foo, keyPath: keyPath) // Good: Optional("baz")
There's not enough in your code snippet for us to see how precisely this might be adapted to your situation.
As Rob Napier said, I wonder if there might be Swiftier approaches to the problem. E.g. when I see switch statements like this, I might tend to gravitate towards enum pattern.