persian language

Let Apple know here:

http://www.apple.com/feedback/iphone.html

Also if you search the app store for "farsi" you may find a keyboard app which meets some of your needs.

You are totally right! The Persian language pack is really needed in the iOS as well as the Persian Keyboard. Furthermore, using the Arabic keyboard is not a good alternative, since the layout is different and the word suggestion system is really disturbing. The best way is giving some feedback to Apple and hope for a change. You can use Apple's feedback form, or find and sign online petitions and requsts, and try to let them know about our need.

Cheers