[SOLVED] Is there a way to embed an assertionFailure into '??' expression?

Is there a way to embed an assertionFailure into '??' expression?

TimeZone(abbreviation: "GMT+1") ?? TimeZone.current

If you want to have a non optional and assert before TimeZone.current fallback is used after ?? what syntax would I use in swift?

something like this

TimeZone(abbreviation: "GMT+1") ?? (assertionFailure("what weird runtime have you've got????"), TimeZone.current)

(which obviously does not compile)

Solution

Try to write extension for Optional where you can handle your case, for example:

extension Optional {
    func rescue(
        _ assertion: String, 
        _ fallback: Wrapped
    ) -> Wrapped {
        guard case let .some(value) = self else {
            assertionFailure(assertion)
            return fallback
        }
        
        return value
    }
}

TimeZone(abbreviation: "GMT+1").rescue("what weird runtime have you've got????", .current) // GMT+0100
TimeZone(abbreviation: "GMT+1lalala").rescue("what weird runtime have you've got????", .current) // what weird runtime have you've got????