无法在 swift 中使用另一个协议扩展协议

Question

Am trying to implement this piece of code in my project.

private protocol AnyOptional {
    var isNil: Bool { get }
}

extension Optional: AnyOptional {
    var isNil: Bool { self == nil }
}

I saw it on SwiftBySundell https://www.swiftbysundell.com/articles/property-wrappers-in-swift/ . But unfortunately am getting this error " Extension of protocol 'Optional' cannot have an inheritance clause ". Although when I tried the same code on a playground it worked just fine. Any idea why?

Answer 1

Check to make sure that the Optional type name isn't being overridden by a third-party module (or your own module even). If it is, then you can use Swift.Optional instead to refer to the Optional enum built into Swift.