CodeIgniter is a really mighty PHP MVC (Model-View-Controller) framework and also among of my personal favourites.
That said, CodeIgniter is around since its initial release in 2006 and is getting constantly release updates, bug and security fixes and serves a home to many mighty websites and portals.
Here are the top most useful cheat sheets for CodeIgniter:
EllisLab – the authors of CodeIgniter – offer an awesome quick overview of library and helpers functions for the version 1.7.1 of CodeIgniter.
Find the printable PDFs here:
CodeIgniter 2.0 Quick Reference
This quick reference includes library, helper and driver functions (such as database and caching). The cheatsheet comes in PNG and PDF and can be easily printed. Find it here.
Cheat Sheet for CI 2.1.0
This is an online only cheat sheet, but provides also cross links to the user help section on Ellislab for each function. It covers classes, drivers, database and helper functions. Available here.
Last, but not least,…
Every CodeIgniter download comes with a folder called “user_guide” where you can look up every function locally.