Q: Do you guys know of any apps or anyone that has made a T9 predictive text program for the iPhone, and if so, when can i get it?
– Kyle
A: Since the iPhone has a full QWERTY on-screen keyboard, there is little demand for a T9 predictive text application. T9 predictive text was designed to handle typing on traditional cell phone keypads where a full keyboard was not available, and very few smart phone devices with full keyboards have any T9 predictive text options available, except in those cases where the phone also has a numeric keypad, such as on the Nokia E90 Communicator.
That having been said, it is unlikely that we will see a T9 program for the iPhone through traditional channels even if a developer had the desire to create one. The current iPhone SDK does not allow background applications or applications that enhance basic system functionality, so with these restrictions in place, such an application would be impossible to design.
It might be more feasible for such an app to be developed unofficially and run on jailbroken iPhones, but at this point there does not appear to have been sufficient incentive to develop such an application.
.