relates to:

• SR-8439 Provide UUID RFC 4122 compliant string

Issue Description:

The RFC for UUID is explicit about the string representation being lowercase:

The hexadecimal values "a" through "f" are output as lower case characters and are case insensitive on input.

But, UUID and NSUUID both return uppercase strings for uuidString, which is then used for UUID's implementation of Encodable and CustomStringConvertible. This makes cross platform issues around case-sensitive storage of UUID s very difficult to completely avoid. For this reason, we're likely going to stop using native UUID in our app and use an internal clone that is the same except it always represents UUID s as lowercase for String representations.

This has been an issue for us for some time, and we now have the time to figure out a more permanent solution to the various workarounds we have in place in our codebase (mostly just avoiding string interpolation with UUID and banning the use of uuidString). Now that Swift is open source and we can see the internals, the change feels pretty straightforward: change the one usage of uuid_unparse to instead be uuid_unparse_lower. But, given the issues we're experience around case-sensitive storage of UUID strings, this feels like a significant breaking change. Additionally, NSUUID's internals would also need to be updated.

I'm happy to make an SE proposal for this, given that I understand the code change in Swift and can present it along with the proposal. That said, there's likely more to do and consider than just that, so I'm starting with this bug 🙂. It would be great to hear from knowledgeable members if this bug is enough, if I should make an SE proposal, or if I should do something beyond that.

Thanks for your consideration!