I just found someone using a regex like this:
NSString *pattern = @"i[\\p{Alphabetic}&&\\p{Uppercase}][\\p{Alphabetic}]+";
[NSRegularExpression regularExpressionWithPattern:pattern options:0 error:NULL];
// Source: http://www.objc.io/issue-5/getting-to-know-textkit.html
// Tested. It actually works.
The regular expression looks pretty cool and readable (supposedly more compatible with Unicode). Where can I find more info on this kind of regex? Is it a Cocoa-only kind of thing?
EDIT: I found a comprehensive answer here.