Impaktor is ready for download on the appstore (as well as ppg , needs headphones to work as microphone to create the signal as a basis for your drum sounds. but they are exiciting n.off to get a phones/ audio combi solution – you need something to split yours signal to still be able to listen to it via your stereo / amp / mixer whatever. (otherwise it would sound from your phones which is of course not enough) – the easy way: put your ipad or iphone on the ground and use the internal microphone and start tap dancing, it works! And you can set your own tune scale which means you only play those tones you selected, sort of quantizing for dynamic play. works nicely without phones as mics.
IPhone version looks like this