XCode building: identical configurations behave differently

I have a superweird problem:

I get a cras开发者_StackOverflow社区h (EXC_BAD_ACCESS) when running my app with Release as active configuration on my 3.1.3 iPhone 3G. (works well in debug configuration or in simulator , works perfectly on device running iOS4).

My first guess was one setting in the Release configuration was erroneous/missing. In order to test it I just made a duplicate of my debug configuration and surprisingly I get the same error (although configuration is just a copy of the one working).

I don't understand why, with configurations that are supposed to be the same, one is working and not the other one.

If someone want to enlighten me, I am banging my head against the wall.

Thank you

NOTE: base SDK is 4.0 and deployment target is 3.0

Perhaps you have an unassigned local variable. Object-C follows how C does this. So in a release version you cannot assume that any local variable is initialised to 0 whilst in debug you can (in this case I would guess a pointer).

EDIT: Pass -Wuninitialized to the compiler (or better -Wall) for the compiler to warn on these Apple gcc man page Note only works if optimizer is on.

You should check for memory leaks and handling of memory warnings. The amount of memory is probably the biggest difference between the environments you quote.

In another scenario I once found out that the simulator was faster, and therefore a certain race condition didn't show up, which did show up on the device. That's the second difference in the environments you quote: speed.

Try to pinpoint your crash and investigate from there. NSLog all didReceiveMemoryWarnings. Look for places where you made assumptions, i.e. about static information.

I fixed the problem.

It was three20 library fault. I had updated to the master branch that support iOS 4 but unfortunately this breaks support for 3.1.3. (thing that is not documented apparently)

Anyway I found this post that helped me to spot the problem. I just had to apply this patch and then I was able to run my project on 3.1.3 devices and iOS4 ones

Weird thing: why was it crashing when I was initializing a UIActionSheet (on a line of code not related at all with the Three20 lib)?

Thank you for your help.