Well, actually i dont think MTA will be possible for iOS, because MTA is only a client for GTA San Andreas and iOS doesnt allow apps to run other apps (u know what i mean).
Maybe with Android it will be possible because its an Open-Source OS, this means that everybody can create their own style and its opened for ideas from everybody.
The only way to get MTA possible on iOS devices, is to make an app that works only with Jailbroken devices.
If MTA team gets in touch with Jailbreakers, i think something will come out