help with the following crashDump

If this is not the right forum to ask such question, please point me to the right one.

The app I am working on uses the location of the user and alert the user when certain condition is met. The alert is in form of vibration and a playback of a small file. During testing on the device, the phone vibrates and the audio clip plays for 2 seconds (the clip is about 9 secs long) and the app crashes. The crashes are consistent on the device. On the simulator, occasionally, I see the crashes but not consistent.

The trigger to set off the alert is in the delegate method of CLLocation class - (void)locationManager:manager didUpdateToLocation:fromLocation:

Here's the code fragment (ivLocMgr is an instance variable)

if ((!ivAlertAlreadyShown)  && (<test for trigger condition)) {
   ivAlertAlreadyShown = YES;

   [self obviousNotification];

   [ivLocMgr stopUpdatingLocation];
   [ivLocMgr release], ivLocMgr = nil;
   }

Can the [ivLocMgr stopUpdatingLocation]; be the root cause?

Any and all help is greatly appreciated. -S-

Incident Identifier: 8875BB08-4DAD-4FC7-8DC6-AA5D52D6FC78
CrashReporter Key:   f995a257bad99baa2fcf0f7d5b0ab3e77dce3a91
Hardware Model:      iPhone2,1
Process:         SAlert [360]
Path:            /var/mobile/Applications/D3B5BAED-036C-4CFE-A735-A61D6ECCDAF6/SAlert.app/SpAlert
Identifier:      SAlert
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2011-08-30 07:35:41.206 -0700
OS Version:      iPhone OS 4.2.1 (8C148a)
Report Version:  104

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x46924508
Crashed Thread:  0

Thread 0 Crashed:
0   libobjc.A.dylib               0x3199f464 objc_msgSend + 16
1   CoreLocation                  0x30e1f430 -[CLLocationManager onClientEventLocation:] + 560
2   CoreLocation                  0x30e1d68e -[CLLocationManager onClientEvent:supportInfo:] + 98
3   CoreLocation                  0x30e1d804 OnClientEvent + 16
4   CoreLocation                  0x30e19522 CLClientInvokeCallback(__CLClient*, CLClientEvent, __CFDictionary const*) + 42
5   CoreLocation                  0x30e1b3cc CLClientHandleDaemonDataLocation(__CLClient*, CLClientLocation const*, __CFDictionary const*) + 196
6   CoreLocation                  0x30e1b512 CLClientHandleDaemonData(__CFMessagePort*, long, __CFData const*, void*) + 286
7   CoreFoundation                0x314913fe __CFMessagePortPerform + 242
8   CoreFoundation                0x314656f8 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 20
9   CoreFoundation                0x3146开发者_如何学运维56bc __CFRunLoopDoSource1 + 160
10  CoreFoundation                0x31457f76 __CFRunLoopRun + 514
11  CoreFoundation                0x31457c80 CFRunLoopRunSpecific + 224
12  CoreFoundation                0x31457b88 CFRunLoopRunInMode + 52
13  GraphicsServices              0x35d664a4 GSEventRunModal + 108
14  GraphicsServices              0x35d66550 GSEventRun + 56
15  UIKit                         0x338d5322 -[UIApplication _run] + 406
16  UIKit                         0x338d2e8c UIApplicationMain + 664
17  StopAlert                     0x00002f76 0x1000 + 8054
18  StopAlert                     0x00002f40 0x1000 + 8000

Thread 1:
0   libSystem.B.dylib             0x31192974 kevent + 24
1   libSystem.B.dylib             0x3123c704 _dispatch_mgr_invoke + 88
2   libSystem.B.dylib             0x3123c174 _dispatch_queue_invoke + 96
3   libSystem.B.dylib             0x3123bb98 _dispatch_worker_thread2 + 120
4   libSystem.B.dylib             0x311e024a _pthread_wqthread + 258
5   libSystem.B.dylib             0x311d8970 start_wqthread + 0

Thread 2:
0   libSystem.B.dylib             0x31166268 mach_msg_trap + 20
1   libSystem.B.dylib             0x31168354 mach_msg + 44
2   CoreFoundation                0x31458648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                0x31457ed2 __CFRunLoopRun + 350
4   CoreFoundation                0x31457c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                0x31457b88 CFRunLoopRunInMode + 52
6   WebCore                       0x33d9f124 RunWebThread(void*) + 332
7   libSystem.B.dylib             0x311df886 _pthread_start + 242
8   libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 3:
0   libSystem.B.dylib             0x31166268 mach_msg_trap + 20
1   libSystem.B.dylib             0x31168354 mach_msg + 44
2   CoreFoundation                0x31458648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                0x31457ed2 __CFRunLoopRun + 350
4   CoreFoundation                0x31457c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                0x31457b88 CFRunLoopRunInMode + 52
6   Foundation                    0x31cf15f6 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 206
7   Foundation                    0x31ccf192 -[NSThread main] + 38
8   Foundation                    0x31cc8242 __NSThread__main__ + 966
9   libSystem.B.dylib             0x311df886 _pthread_start + 242
10  libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 4:
0   libSystem.B.dylib             0x3118a68c select$DARWIN_EXTSN + 20
1   CoreFoundation                0x3148f662 __CFSocketManager + 582
2   libSystem.B.dylib             0x311df886 _pthread_start + 242
3   libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 5:
0   libSystem.B.dylib             0x31166268 mach_msg_trap + 20
1   libSystem.B.dylib             0x31168354 mach_msg + 44
2   CoreFoundation                0x31458648 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                0x31457ed2 __CFRunLoopRun + 350
4   CoreFoundation                0x31457c80 CFRunLoopRunSpecific + 224
5   CoreFoundation                0x31457b88 CFRunLoopRunInMode + 52
6   MapKit                        0x347a2906 TileCachePrivate::runCacheThread() + 274
7   MapKit                        0x347a27ea _runCacheThread(void*) + 2
8   libSystem.B.dylib             0x311df886 _pthread_start + 242
9   libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 6:
0   libSystem.B.dylib             0x311de9f0 __semwait_signal + 24
1   libSystem.B.dylib             0x311937ec _pthread_cond_wait + 748
2   libSystem.B.dylib             0x311933d2 pthread_cond_wait + 26
3   QuartzCore                    0x30a925dc CA::DispatchGroup::thread(void*) + 84
4   QuartzCore                    0x30a5f01a thread_fun + 10
5   libSystem.B.dylib             0x311df886 _pthread_start + 242
6   libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 7:
0   libSystem.B.dylib             0x31166268 mach_msg_trap + 20
1   libSystem.B.dylib             0x31168354 mach_msg + 44
2   libSystem.B.dylib             0x3118af5a thread_policy + 118
3   libSystem.B.dylib             0x3118aed2 pthread_setschedparam_internal + 62
4   libSystem.B.dylib             0x3118ae0e pthread_setschedparam + 70
5   TextInput                     0x31e8128a KB::kb_set_thread_priority(int) + 18
6   TextInput                     0x31e71f74 KB::BackgroundLoad(void*) + 84
7   libSystem.B.dylib             0x311df886 _pthread_start + 242
8   libSystem.B.dylib             0x311d4a88 thread_start + 0

Thread 0 crashed with ARM Thread State:
    r0: 0x0403000f    r1: 0x33baf8ef      r2: 0x30e4bff6      r3: 0x00000001
    r4: 0x46924500    r5: 0x30e1d7f5      r6: 0x00a01c64      r7: 0x2fdfec44
    r8: 0x00000000    r9: 0x040fc098     r10: 0x00000000     r11: 0x00000000
    ip: 0x3e16c584    sp: 0x2fdfeaa0      lr: 0x30e1f437      pc: 0x3199f464
  cpsr: 0x200f0030

---

Found the answer on Apple Developers' Forum:

  I needed to set the coreLocation instance's delegate to nil, when the alarm was triggered.

---

There isn't enough code there to properly determine the cause of the abort. The error you are getting is telling you that you are trying to access a variable that has already been released. I would start there and make sure you haven't released your location manager or some other variable there.