There are already ways you can do this. https://nshipster.com/uuid-udid-unique-identifier/ https://nshipster.com/uuid-udid-unique-identifier/ The easiest is w

There are already ways you can do this. https://nshipster.com/uuid-udid-unique-identifier/ https://nshipster.com/uuid-udid-unique-identifier/ The easiest is with the identifierForVendor property of [UIDevice] which identifies that specific device for your software, but is not shared with other vendors. So you can ban Bob's iPhone across all your apps, but that ID isn't useful to other vendors.