I've attached a .zip archive below, I've modified a file for easy gil, easy experience or both. Please do not distribute or download these files unless you purchased the game and are using it as a backup.
Enough of the jabber, here's the sauce:
Note: Please read the comments for solutions to any problems you may encounter, this hack should work on all devices. Make sure you backup your original ff3 file located in
/private/var/mobile/Applications/AEFBF631-CBE8-4A05-8ABA-8680D2F58301/ff3.app/
The cheats and instructions can be downloaded at any of these mirrors
Download
http://rapidshare.com/files/455617063/ff3cheats.zip
http://www.megaupload.com/?d=BO6YUNMM
http://depositfiles.com/en/files/nwxhdwkeo
http://hotfile.com/dl/113098635/fcf3d64/ff3cheats.zip.html
http://www.zshare.net/download/88551746cd487b93/
http://uploading.com/files/m242f2m9/ff3cheats.zip/
http://fileape.com/dl/BztIDN9NggxGm3vM
After you replace the file, you should reboot your iPhone and then start the game, after that you will want to get into a random battle and win for the cheat(s) to take effect.
If you're having problems with it working, FrederickVntr18 posted a helpful video showing you how to install the hack step-by-step at the following link http://www.youtube.com/watch?v=4E7JjpBQyhY, enjoy!