Nobody should work for months on an iPhone app. The platform is not friendly to that style of app. Work for weeks, launch and test.
I don't know how friendly the platform is for that approach, either. Fast iteration works better when you don't have the bottleneck of app store reviewers.
Because if you spend months and release to the great app store silence, it will break you faster than a 5 ton pin would break a camels back.
On the lighter side, there is a chance that Apple might release some other gadget and people will go after it if you are going to take months to release an app for iphone ;)