Why I've got no crontab entry on OS X when using vim?

Question

I would like to use cron on my Mac. I choose it over launchd, because I want to be able to use my new knowledge on Linux as well. However, I cannot seem to get

Answer 1

I did 2 things to solve this problem.

1. I touched the crontab file, described in this link coderwall.com/p/ry9jwg (Thanks @Andy).
2. Used Emacs instead of my default vim: EDITOR=emacs crontab -e (I have no idea why vim does not work)

crontab -lnow prints the cronjobs. Now I only need to figure out why the cronjobs are still not running ;-)