It is very easy with latest tmux version to get working vim and MacVim with system buffers. You need just follow the simple steps and get it working!
Install or update tmux:
brew install tmux (or brew upgrade tmux)
Install workaround for accessing clipboard in OSX:
brew install reattach-to-user-namespace
Use copy-pipe command to setup v/y vim keys in tmux.conf
bind -t vi-copy 'v' begin-selection
bind -t vi-copy 'y' copy-pipe "reattach-to-user-namespace pbcopy"
Tweak your .vimrc to use unnamed clipboard:
Create new alias for mvim and vim in .zshrc or .bashrc:
alias mvim="reattach-to-user-namespace mvim"
alias vim="reattach-to-user-namespace vim"
That's it! Now every yank (y, yy) or delete (d, dd) commands will copy data to system buffer.