Mac OS X Crashlog Debug Objective C

I'm trying to debug by using a Crash Log that has been sent by a user. Problem is that I can't reproduce the crash, which means that I can't use Xcode to debug the crash withNSZombieEnabled or the debugger.

The log gives me an idea of what the cause of the crash is (release something too early?), but I don't know where it's happening.

I've tried the atos tool, but whatever hex I enter (0x94e10ed7 for example), it just returns the same hex I entered and nothing else (unlike in Apple's tutorial here: http://developer.apple.com/tools/xcode/symbolizingcrashdumps.html)

How can i find out where this problem is happening?

Here's the crashlog:

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x000000004d555478
Crashed Thread:  0  Dispatch queue: com.apple.main-thread

Application Specific Information:
objc_msgSend() selector name: respondsToSelector:


Thread 0 Crashed:  Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib                 0x94e10ed7 objc_msgSend + 23
1   com.apple.CoreFoundation        0x975ee5f2 _CFStringAppendFormatAndArgumentsAux + 3138
2   com.apple.CoreFoundation        0x975ed979 _CFStringCreateWithFormatAndArgumentsAux + 105
3   com.apple.Foundation            0x95b51d23 -[NSPlaceholderString initWithFormat:locale:arguments:] + 163
4   com.apple.Foundation            0x95b51bd6 +[NSString stringWithFormat:] + 88
5   com.myapp.test      0x0006f7c0 -[File5 firefoxCookies] + 539
6   com.myapp.test      0x0006f25b -[File5 numberOfCookies] + 34
7   ...yapp.test    0x00003754 0x1000 + 10068
8   com.apple.CoreFoundation        0x9762e9b4 -[NSSet makeObjectsPerformSelector:] + 196
9   com.apple.AppKit                0x9314521c -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1566
10  com.apple.AppKit                0x931431f4 l开发者_开发百科oadNib + 257
11  com.apple.AppKit                0x931425ed +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:] + 228
12  com.apple.AppKit                0x931424fe +[NSBundle(NSNibLoading) loadNibFile:externalNameTable:withZone:] + 158
13  com.apple.AppKit                0x93142449 +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 383
14  com.apple.AppKit                0x9313f24d NSApplicationMain + 434
15  ...yapp.test    0x00002d48 0x1000 + 7496
16  ...yapp.test    0x00002cfe 0x1000 + 7422

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Most of the log is already symbolized. The crash is occuring after calling [NSString stringWithFormat:] from the firefoxCookies instance method of the class File5.

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the easy way to see it to see the last function called from your source file and it will be followed by "com.myapp.test" or what ever is your apps or company name..in case you have fed it