Apple iOS devices don't support the bluetooth serial protocol, so outside of a couple of Apple approved bluetooth GPS devices, they won't work with an iPad or iPhone. The only ones I can think of at the moment are the Garmin GLO, and two that I don't know the models of, Bad Elf and Dual. I know the latter two are sold at pilot suppliers like Sporty's. They usually run ~$100, quite a bit more than a generic BT GPS, but most of that is due to the "Apple Tax".