Printing to Epson TM-T88V receipt printer from iOS

Question

Does anyone know how to get CUPS running on iOS? We are trying to print to a networked Epson receipt printer ( TM-T88V) from the iPad, using CUPS or other method but we are running into a brickwall getting CUPS to run on iOS. I know for a fact that this can be done, as an iPad app can already do it just by passing in the IP address of the printer. How are they doing this?