Multi login in codeignter

As includebeer pointed out, the A3M code is probably the best we can do for you. In most cases the biggest step in going from a single authentication method to multiple methods is to move the fields currently required for authentication out of your users table. Once you've put them in a separate table with a user_id foreign key to look up the user information, it's relatively simple to add additional methods of authentication. The hardest part at that point is figuring out how to do something specific like Facebook authentication, and you can probably find tutorials for each form of authentication you need to support, you'll just have to rework them for your specific needs.

Bonfire

Practical CodeIgniter 3
CodeIgniter Testing Guide