There is no API, it's all reverse-engineered (AFAIK). I've been using the XVim plugin full time for the past year, and it's been very, very stable lately. It still crashes from time to time, but that can just as well also be XCode.
This man is correct - there is no plugin API and everything is reverse-engineered.
XVim is built on an internal layer that doesn't know about Xcode, then all operations are funnelled through an interface that does know about Xcode specific things. This makes it a little easier to upgrade should they decide to refactor Xcode's internal implementation. Still, Xcode's internals haven't really changed that much since 4.2+.
Source: XVim contributor, especially to its architecture
I just tried XVim for the first time because of this post. This unbelievably well integrated into XCode, and the source code is very clean, especially for obj-c.
Yeah, and the guy has been working for a long time on a huge refactor that will bring column selection, global marks, better window management, and a couple of other things. Not to mention that it may be easier to extend it. This is currently the second best vim implementation after evil-emacs, imho.
I've used AppCode for a couple of months last year and tried again with 2.0 this year, but I really didn't like IdeaVim, and I didn't look like easy to extend.
Unfortunately I'm not involved anymore, it was hard to keep up motivation since I started using the excellent AppCode. Although I do think XVim is a lot better than IDEAVim.
