I apologize in advance if this subject has already been discussed and decided (as far as I can tell, the mailing list archives go back only about 60 days)…
When running through the Swift Tour portion of the Swift eBook, on page 10 there is a code snippet showing an example of the switch statement. While typing that into an Xcode playground, I get a code completion popup on the “hasSuffix” method and the documentation says “Returns true iff self ends with suffix.” This looks like a typo. I know that it means “If and Only If” but to a less experienced developer this is likely to be misunderstood, especially as I can find no explanation for “iff” anywhere in the documentation.
The source of this documentation nugget is a comment in /stdlib/public/core/StringLegacy.swift, so I think discussion of the topic is relevant here.
Swift is touted as being friendly to new programmers and I don’t think it is reasonable to expect new programmers to understand “iff” and I also don’t think it is reasonable to spend a paragraph explaining “iff” at the beginning of an introduction to Swift, thus I suggest removing “iff” from all code comments that are likely to become user-facing documentation (the triple slash). Or at the very least, user-facing documentation that is likely to be read by beginners.
A quick grep of the source gives me somewhere in the neighborhood of 130 instances of “iff” in a triple-slash comment, and I am more than happy to make all of the changes and submit pull requests. Before taking on that work, however, I would like to know if such a change would be welcome or if anyone has a better idea, etc.