That's fine and dandy, and I love Heroku, but recently I've been falling in love with Parse(.com) for iOS development. True, Heroku gives me more control over how I want to handle requests, but Parse has so much more built in and is simpler to integrate. What I've been doing with iOS & parse is hook a heroku app to Parse's REST API whenever I want to manipulate the data that is sent beyond what parse allows.
On top of that, building this out is unlikely to match much of parse's capabilities unless a huge amount of work is put in (by you). And once it's 'done', it will no longer have that magical property of getting better without more work on your part, whereas Parse will continue to grow and kick (even more) ass.
There's almost certainly some part of this approach that would be fun, but I can't really think of it off the top of my head.
with apologies to patio11 for (mis)appropriating his meme.