How to check if `Any(not Any?)` is nil or not in swift

Question

I'm working with the Mirror in swift, I found Mirror.Child is very strange, the label is nullable, but the value seems not nullable.

public typealias Child = (label: String?, value: Any)

I don't know how to check if the value is nil or not.

let b: Bool? = true
let a: Any = b
print(a == nil) // false

I have one solution:

print(String(describing: a) == "nil") // true

but it is obviously not a good solution.

what is the best way to check if a is nil or not ?

Let me put more detail,

let mirror = Mirror(reflecting: object) // object can be any object.
for child in mirror.children {
    guard let label = child.label else {
        continue
    }
    // how to check if the value is nil or not here ?
    setValue(child.value, forKey: label)
}

Answer 1

Using if case:

You can use if case Optional<Any>.none = a to test if a is nil:

var b: Bool?
var a = b as Any
if case Optional<Any>.none = a {
    print("nil")
} else {
    print("not nil")
}

nil

b = true
a = b as Any
if case Optional<Any>.none = a {
    print("nil")
} else {
    print("not nil")
}

not nil

---

Using switch:

You can use the pattern test with switch as well:

var b: Bool?
var a = b as Any

switch a {
case Optional<Any>.none:
    print("nil")
default:
    print("not nil")
}

nil