Great iPhone questions... for exercise and learning, not interview
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 http://stackoverflow.com/questions/1282830/uiimagepickercontroller-uiimage-memory-and-more - which has a lot of questions and a lot of great information. I voted it up.

I'm thinking of sending out one of these topics about every week and then having a discussion about it towards the end of the week with some examples. Maybe assign a short presentation on a rotating basis so someone gets the job of delivering a 10-minute presentation about the topic, prizes awarded etc. - then when some task comes up involving that topic we may not have an expert but we at least have someone who knows where to start looking for answers. And maybe is keen to find out more based on that exercise.

stackoverflow, while it has "great questions", has a lot that are not so great and these scroll by in huge numbers daily. In iPhone-tagged questions sorted by votes I'm seeing very few of the kind of questions I want. I'm going to look further at some of the top-ranked questions here of course but these are the questions people had to ask, not necessarily the questions that others might get the most benefit from. 

There are lots of exercises for "programmers" around but those are not what is needed. I want this to be iPhone specific. We come from a range of backgrounds and are all decent programmers already.

So - what are some things about iPhone development that YOU think are worth knowing? Can those things be phrased in the form of a question that leads an enterprising programmer to a satisfying answer? What made you stop and think, saved you days, pushed you in another direction that was fun and/or profitable, increased your knowledge or just made you feel good for having discovered the answer?
Great iPhone questions... for exercise and learning, not interview
===

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 http://stackoverflow.com/questions/1282830/uiimagepickercontroller-uiimage-memory-and-more - which has a lot of questions and a lot of great information. I voted it up.

I'm thinking of sending out one of these topics about every week and then having a discussion about it towards the end of the week with some examples. Maybe assign a short presentation on a rotating basis so someone gets the job of delivering a 10-minute presentation about the topic, prizes awarded etc. - then when some task comes up involving that topic we may not have an expert but we at least have someone who knows where to start looking for answers. And maybe is keen to find out more based on that exercise.

stackoverflow, while it has "great questions", has a lot that are not so great and these scroll by in huge numbers daily. In iPhone-tagged questions sorted by votes I'm seeing very few of the kind of questions I want. I'm going to look further at some of the top-ranked questions here of course but these are the questions people had to ask, not necessarily the questions that others might get the most benefit from. 

There are lots of exercises for "programmers" around but those are not what is needed. I want this to be iPhone specific. We come from a range of backgrounds and are all decent programmers already.

So - what are some things about iPhone development that YOU think are worth knowing? Can those things be phrased in the form of a question that leads an enterprising programmer to a satisfying answer? What made you stop and think, saved you days, pushed you in another direction that was fun and/or profitable, increased your knowledge or just made you feel good for having discovered the answer?