Is it not possible to map MFi controllers to on-screen inputs?

I recently bought a Moga Ace Power, and loved using it with PPSSPP as well as the games that are compatible with MFi controllers. I was, however, disappointed that it was not supported by several apps, including Final Fantasy 4: The After Years (the other Final Fantasy games are supported) and Adventure Bar Story. I would've spent hours on the latter if not for the fact that it is not supported. The app hasn't been updated for a long time, so I don't think the developers are planning to update it any more. I was wondering if there was some way the controller can be made compatible with the app by mapping each button to a tap on the on screen controls. Has anyone tried that before, or is it not possible?

The Nvidia Shield tablet does this, I think it's built into the OS. A similar feature for IOS would be awesome!

Yeah, unfortunately, there's no way to manually map controllers to the touch screen. I could see Apple not wanting to add such a user-unfriendly feature, but at least they could bury it in Accessibility settings somewhere. Maybe someday...