get the GUID in macOS using Swift | Apple Developer Forums

In WWDC 2019 session In-App Purchases and Using Server-to-Server Notifications they say that in our server we must have in a database a field for the userId.

I think that a good candidate to use as userId for iOS and tvOS would be identifierForVendor:

UIDevice.current.identifierForVendor?.uuidString

And for macOS the GUID but the info that I found in the Apple documentation uses Objective-C instead of Swift:

https://developer.apple.com/library/archive/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateLocally.html#//apple_ref/doc/uid/TP40010573-CH1-SW14

Is there info about who to do it using Swift somewhere or should I use Objective-C?

I also found some code of Swift in github, but I do not now if really get the real Mac UUID and also if this method is allowed by Apple.

    func macSerialNumber() -> String {
        let platformExpert: io_service_t = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));

        guard let serialNumberAsCFString = IORegistryEntryCreateCFProperty(platformExpert, kIOPlatformSerialNumberKey as CFString, kCFAllocatorDefault, 0) else { fatalError("Can not get serialNumberAsCFString") }

        IOObjectRelease(platformExpert);

        return (serialNumberAsCFString.takeUnretainedValue() as? String) ?? ""
    }

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        print("Unique Device Identifier: \(macSerialNumber())")
    }