I'm really liking the example by @Thruston in the comments above, so with all credit to their answer, I'd like to expand it here including installation and setup steps.
Combined with ideas from: Dianaci's Vim Setup, I will outline the 5 minutes of steps it took to get my system optimal.
- Install Skim
- Open Skim and go to Preferences > Sync and check "Check for file changes" and "Reload automatically"
- Install MacTex which will provide xelatex, latex, etc., if you don't already have xelatex on your system.
- Create a VIMRC file at ~/.vimrc if you don't have one already.
- Add the following:
" Mappings for compiling Latex file
autocmd FileType tex nmap <buffer> <C-T> :!xelatex %<CR>
autocmd FileType tex nmap <buffer> T :!open -a Skim %:r.pdf<CR><CR>
These create commands for quickly running xelatex from within VIM or MacVIM by pressing Ctrl-T and for opening the resulting PDF in Skim (Shift-T).
Once you have completed those steps, open VIM or MacVim (be sure to close and re-open if you just created your .vimrc file so that they pick up the changes). Then open a .tex file and hit Ctrl-T to compile it to PDF. The xelatex output will require you to hit return to get back to the VIM interface. Then hit Shift-T to open the PDF in Skim.
Skim will update automatically from that point on whenever you hit Ctrl-T to recompile the .tex file.
Thanks to @Thruston from the comments above and to DianaCai for the additional VIM command ideas. Hope you enjoy. I certainly do.