Back in the old days, before the Emoji keyboard came standard on iOS, you could download an app that allowed you to enable and use the Emoji keyboard. Following this same concept, is it possible for me to define my own keyboard, with my own symbols that users can choose to make available in their iPhone settings?
This is for non-jailbroken iOS devices. If there's a solution for jailbroken devices, I'd take that too (for educational purposes).