It doesn't seems that a lot of iOS developers are using VIM, so there aren't many resource there. I've been using cocoa.vim for ages and it hasn't been updated for 4 years, while a lot of new features are introduced like ARC, block, etc. In this way you can make things well organized:
~/.vim$ ls autoload/
pathogen.vim
~/.vim$ ls bundle/
cocoa.vim vim-objc
Search keywords for the repos on github. Also don't forget to add this to your .vimrc:
execute pathogen#infect()
PS: cocoa.vim - https://github.com/msanders/cocoa.vim
