Vim: How To Fold Functions

The is really a tip on how to fold any code block including functions. Navigate your cursor somewhere inside of the code block you want to fold, make sure you are in command/normal mode (press escape if you need to) then type zfa}

To save your folds between vim sessions you need to issue the command :mkview otherwise when you close vim your folds will be lost (your folds, not your code). To make life easier on you, you can have your folds automatically saved for you by adding this to your .vimrc file

au BufWinLeave * mkview
au BufWinEnter * silent loadview

Source: Refreshingly Blue » Blog Archive » Vim: How To Fold Functions.