Recording a Walkthrough

Hi all, Maybe this is covered elsewhere, maybe it's really easy, maybe it's impossible...who knows? I'm clueless, and am turning to you all for help. I'm interested in recording a "Let's Play"-style walkthrough of The Nightjar for some sighted friends of mine without iOS devices; they're really interested in the concept, and I think it'd be a great way to spread awareness about the commercial viability of audiogames. Anyway, I'm trying to figure out a way to record the stereo output of my iPhone (obviously this is needed to get the spatial sound that makes Nightjar what it is), plus my voice. Not really sure what app and hardware setup to use. Advice would be appreciated - has anyone done something like this before? Thanks! ~ JWB