What is a good Objective-C App to get started on?

I am starting Objective-C with intention to get into extensive iPhone Development. Where are some good places to start? I have purchased 2 books:

Programming in Objective-C by Stephen Kochan and Beginning iPhone Development开发者_Go百科 by Dave Mark and Jeff LaMarche

The tutorials are good, I would just like to get into my own thinking, as it is hard to wrap my head around things in others words.

Any ideas?

I'd say a basic twitter client. This will typically expose you to UITableViews, UINavigationController and its stack as well as basic network communication. All of which are corner stones of almost any iPhone app.

A tweeting tip calculator that does unit conversion on flickr images.

A calculator would be a good starting example.

I would write something that is useful to YOU, something that you don't intend on putting on the app store. From there you should master basic concepts that you can later use on an application that you submit to the app store that has a use to other people, not just you.

You can always just solve a number of Project Euler problems - though that's more for learning the language and less for iPhone/GUI development. Though if you manage to run some of those on the iPhone in a reasonable time...

Actually, I found that after solving the problems myself, I could always learn from others' solutions...

Otherwise, you can always go with the the calculator, in fact, I hear there is no really good, usable scientific calculator for the iPhone, if you can believe that. :)