Non-app related question, is there a stock service that will slice together and create the animated screen transitions you have? I am about to put together a si

Non-app related question, is there a stock service that will slice together and create the animated screen transitions you have? I am about to put together a site for an iOS app and I'm guessing that this is common enough that I can spend a little money and save a lot of time. (any link related to buying designs/layouts welcome too)