If you get an EXC_BAD_ACCESS with the following stack trace, activating NSZombie could help you to find the object causing the problem.

0x01285a63 in objc_msgSend
0x0580e400 in ??
0x0105fb8d in _ CFAutoreleasePoolPop
0x00022443 in -[NSAutoreleasePool release]
0x002d3bf2 in _ UIApplicationHandleEvent
0x018cca36 in PurpleEventCallback
0x01105064 in __ CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__
0x010656f7 in __CFRunLoopDoSource1
0x01062983 in __CFRunLoopRun
0x01062240 in CFRunLoopRunSpecific
0x01062161 in CFRunLoopRunInMode
0x002cafa8 in -[UIApplication _run]
0x002d742e in UIApplicationMain
0x00001ca0 in main at main.m:14

You can activate NSZombie by doing the following:

1. Get info of the executable.
2. Go to the arguments tab.
3. In the “Variables to be set in the environment:” section add:
4. Name: NSZombieEnabled Value: YES

Then you can run  your app and when it crashes you should see an log entry in the console about the object causing the problem.