What is NSCFString? I can't find anything useful about it in the documentation, developer.apple and google, but everyone has questions about it. My problem with it is that I get such a string in my NSTextView subclass in the method insertText:. I was expecting NSString or NSAttributedstring (or their mutable brothers and sisters), not NSCFString. Where is the API for this beast? How am I supposed to (correctly) use it.