Is there any forum software based on codeigniter ? free or commercial ?
I haven't tried either of these myself but i've heard very good things and you should take the time to investigate them both:
Dove Forums Dove Forum is fairly new, but growing and seems to have fairly strong support from the Code Igniter community at the moment.
Pyro CMS Pyro CMS is made by some of the top contributors to the Code Igniter community and gets alot of plaudits.
It's a fully fledged CMS rather than a forum script, but it has a forum add on which you can download to add that functionality.
You could check out MyForum (https://github.com/EllisLab/CodeIgniter/wiki/MyForum) - it is reasonably simple and I have had very good experiences with it in the past! It's free as well :)
Yep http://codeigniter.com/wiki/MyForum/ is nice and you can get all the necessary information about the coding and other practices using codeigniter over here.
not sure how helpful this is to you now, but Elite Bulletin Board(http://elite-board.us) is switching to CodeIgniter for their next version.
while its still in development, the code is in SVN if you wanted to look at it.
来源：https://stackoverflow.com/questions/5523151/is-there-any-forum-in-codeigniter-php