If you are making this app with delusions of wealth and grandeur, I'd advise you to give up now, there is such a gigantic, enormous number of study apps that I would recommend you give up on the idea and find something a bit more unique and interesting.
But if you are new to iOS development and you're looking to learn the technology, then yeah, a study app is a good way to get started. I would recommend getting very well versed in UITextViews, how they work, and so on, because they can be quite powerful and flexible if you implement it correctly.