Before you do anything, decide not only the app's purpose but also on the intended audience.
Developing useful applications for any platform takes more than just the ability to write lines of code. No matter what you think your Apple iOS app is going to do, you have to at least have a plan of action. You have to decide not only the app's purpose but also on the intended audience. One of the best ways to define those two vital characteristics is with the Application Definition Statement.
The Apple iOS Developer Library has an in-depth article detailing app design strategies, including the formulation of the Application Definition Statement, which I encourage every iOS App developer to read thoroughly. Establishing a strategy before you begin writing code will save you headaches in the long run.
So, with that being said, I am curious as to how many iOS app developers have taken the time to create a formal Application Definition Statement?
And, to take the discussion a bit further, perhaps you would like to share your Application Definition Statement for your last project with your peers in the discussion forum? Did you have to change direction and make adjustments while working on your last app? Would a better early plan have helped or do you prefer to fly by the seat of your pants?