iPhone上有哪些关于锻炼的好问题?

In a small team where everyone is coding away on a project for a little while I want to encourage some different thinking to keep people increasing their iOS knowledge as well as to get a bit more variety in their daily activities. I'm not looking for interview questions involving manhole covers, nor very specific questions about whether drawRect: is part of UIView or UIViewController. I'm looking for questions more along the lines of In a small team where everyone is coding away o