Debugging EXC_BAD_ACCESS from a NSString

I had a EXC_BAD_ACCESS message in my console. I read about the environment variables NSZombieEnabled and MallocStackLoggingNoCompact on this site. I created my environment variables: NSZombieEnabled = YES and MallocStackLoggingNoCompact = 1. In the console, I saw

2010-03-01 19:13:46.924 CruzNomad[7952:207] * -[CFString stringByAddingPercentEscapesUsingEncoding:]: message sent to deallocated instance 0x58448e0

Then at the (gdb) prompt, I did info malloc-history 0x58448e0, which gave me:

Alloc: Block address: 0x058448e0 length: 64
Stack - pthread: 0xa0b33500 number of frames: 25
    0: 0x98e089bc in malloc_zone_malloc
    1: 0x21516aa in _CFRuntimeCreateInstance
    2: 0x2152bf8 in __CFStringCreateImmutableFunnel3
    3: 0x21567d9 in CFStringCreateCopy
    4: 0x21742fc in _CFStringCreateWithFormatAndArgumentsAux
    5: 0xdb546 in -[NSPlaceholderString initWithFormat:locale:arguments:]
    6: 0xdb4d8 in +[NSString stringWithFormat:]
    7: 0x23aa3 in -[BuisnessCardViewController viewDidLoad] at /Users/.../Classes/BuisnessCardViewController.m:85
    8: 0x3d6796 in -[UIViewController view]
    9: 0x347b4 in -[gm_menuViewController btn5_Pressed:] at /Users/.../Classes/menuViewController.m:535
   10: 0x357459 in -[UIApplication sendAction:to:from:forEvent:]
   11: 0x3baba2 in -[UIControl sendAction:to:forEvent:]
   12: 0x3bcdc3 in -[UIControl(Internal) _sendActionsForEvents:withEvent:]
   13: 0x3bbb0f in -[UIControl touchesEnded:withEvent:]
   14: 0x370e33 in -[UIWindow _sendTouchesForEvent:]
   15: 0x35a81c in -[UIApplication sendEvent:]
   16: 0x3610b5 in _UIApplicationHandleEvent
   17: 0x2984ed1 in PurpleEventCallback
   18: 0x2197b80 in CFRunLoopRunSpecific
   19: 0x2196c48 in CFRunLoopRunInMode
   20: 0x298378d in GSEventRunModal
   21: 0x2983852 in GSEventRun
   22: 0x362003 in UIApplicationMain
   23: 0x2c8c in main at /Users/.../source/main.m:14
   24: 0x2bfa in start

Line 7 says the problem was in line 85 of BuisnessCardViewController.m. That line is here:

fullAddress = [NSString stringWithFormat:@"%@ %@", fullAddress, myString];

I'm appending the contents of fullAddress and myString and storing it back in fullAddress.

If I'm interpreting this correctly, it appears that after this line, fullAddress is deallocated. When I drop a breakpoint and hover over the variable, its value says "out of scope."

fullAddress works later in this method. I use it to send to send to Google for reverse geocoding in line 164 of the same method.

NSString    *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%@&output=csv", [fullAddress stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

Even here, it says "out of scope." I'm stumped...any advice??

Thanks!

Thomas

Answers


In most cases this happens when you don't retain an attribute which is object and send late messages to it in other methods, late.

So, where some strings are initialized try:

[fullAddress retain];

or

[myString retain];

depending which one is initialized in other method.


Have you tried appending string with format?

fullAddress = [NSString stringWithFormat:@"%@ %@", fullAddress, myString];

with:

- (NSString *)stringByAppendingFormat:(NSString *)format ...

like this:

[fullAddress stringByAppendingFormat:@" %@", myString];

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