swiftdynamic

Determine if Any.Type is Optional

I’m trying to determine if a given type t (Any.Type) is an optional type, I’m using this test

t is Optional<Any>.Type

but it returns always false.

So is there any way to achieve this?

Solution

  • Assuming that what you are trying to do is something like this:

    let anyType: Any.Type = Optional<String>.self
anyType is Optional<Any>.Type // false

    Sadly swift currently (as of Swift 2) does not support covariance nor contravariance and type checks directly against Optional.Type cannot be done:

    // Argument for generic parameter 'Wrapped' could not be inferred
anyType is Optional.Type // Causes error

    An alternative is to make Optional extend an specific protocol, and check for that type:

    protocol OptionalProtocol {}

extension Optional : OptionalProtocol {}

let anyType: Any.Type = Optional<String>.self
anyType is OptionalProtocol.Type // true