Jon: That explains the general paranoia I feel whenever doing search and replace. Thanks.

Aaron: My question was not why ICU so much as why not ICU in both the search and replace strings. If they use ICU syntax for the match pattern, you'd think they also use it for the replace pattern. Thanks for the link. Uwe Hoffman also did a similar thing: http://www.codemanic.com/blog-archives/000088.html

Also, for those who only need to do straight regex matching (no capture groups or replacement), NSPredicate (which is also backed by ICU) can be used.