iPhone App Crashing during navigation

I have a tough problem (tough for me since I'm a newb.). I have a table view app that I'm working on. It starts with a table and you navigate down to a view controller. In that view controller I'm using some sample code hooked into a button that will add a contact to the iPhone address book.

My problem is when the user navigates back to the table of data, the app crashes. Is there any advice someone can provide? Or, maybe someone I could send me code for review?

Update*

Here's the information from the console.

[Session started at 2010-07-20 22:51:46 -0500.]
2010-07-20 22:51:49.621 Infinite Possibilities[5882:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSPlaceholderString initWithString:]: nil argument'
*** Call stack at first throw:
(
 0   CoreFoundation                      0x025ff919 __exceptionPreprocess + 185
 1   libobjc.A.dylib                     0x0274d5de objc_exception_throw + 47
 2   CoreFoundation                      0x025b8078 +[NSException raise:format:arguments:] + 136
 3   CoreFoundation                      0x025b7fea +[NSException raise:format:] + 58
 4   Foundation                          0x0006869c -[NSPlaceholderString initWithString:] + 105
 5   Infinite Possibilities              0x00003b90 -[RootViewController tableView:didSelectRowAtIndexPath:] + 3405
 6   UIKit                               0x0034c718 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1140
 7   UIKit                               0x00342ffe -[UITableView _userSelectRowAtIndexPath:] + 219
 8   Foundation                          0x00059cea __NSFireDelayedPerform + 441
 9   CoreFoundation                      0x025e0d43 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
 10  CoreFoundation                      0x025e2384 __CFRunLoopDoTimer + 1364
 11  CoreFounda开发者_如何学编程tion                      0x0253ed09 __CFRunLoopRun + 1817
 12  CoreFoundation                      0x0253e280 CFRunLoopRunSpecific + 208
 13  CoreFoundation                      0x0253e1a1 CFRunLoopRunInMode + 97
 14  GraphicsServices                    0x02e642c8 GSEventRunModal + 217
 15  GraphicsServices                    0x02e6438d GSEventRun + 115
 16  UIKit                               0x002e8b58 UIApplicationMain + 1160
 17  Infinite Possibilities              0x00002834 main + 102
 18  Infinite Possibilities              0x000027c5 start + 53
)
terminate called after throwing an instance of 'NSException'

Usually a crash means you have some sort of memory problem or calling a undefined function(sending a message that is not answered by the receiver).

Are trying to read from a pointer to an object that was released already? Are you trying to send a message to an object that is not answering to it?

The good news is that you have a lot of good tools to find out exactly what it is:

First of all, open the console (Shift + Command R) and see if there is a message or stack trace when your app crashes. If there is no message, run the debugger (Shift + Command Y) and see where it stops on the crash.

Finally, if you see the status bar of XCode, it will tell you a bit of information about the crash (the message that was send about the crash, could be a EXEC_BAD_ADDRESS or some other thing.

Sadly, without your code or any of this information this is all I can do to help you. I would suggest not only copy and pasting but really understanding what that code is supposed to be doing and also learning how to debug your code.

For good resources I would recommend the Itunes U Standford Iphone development class and/or reading a good book about it(I read the Head First Iphone book and I love the series but didn't really like this one).