In MAC 10.10.5 MyApp crashes - objective-c

Question

MyApp has crashed and I have collected the below crash log from that MAC book. As it is mentioned the application crashed at thread 3, I could not able to figure out what has happened,
I was suspecting it could be because of a NSTimer Lock and tryLock, but not sure how to figure it out. Crash is not happening with all MAC book but only to a certain set of users all of them are just migrated to MAC 10.10.5. But I have also other MAC book which has MAC 10.10.5 in which MyApp is running perfectly.
can anyone help me out to find the problem?
If i looked at the code at [AppMainController sendPacketForLoginStatus] + 1644
it is just a comment line just after the curly brace { starting of an else{}
if
...
else
{
<< line no: 1644>> // Change the status icon if necessary when losing the focus
[self performSelectorOnMainThread:#selector(showClickStatusIconWhenLoseFocusInThread) withObject:nil waitUntilDone:NO];
...
Crash log:
Process: MyAppAgent [581]
Path: /Applications/MyAppAgent.app/Contents/MacOS/MyAppAgent
Identifier: com.Mycmp.MyApp.MyAppAgent
Version: 1.0.0.1
Code Type: X86 (Native)
Parent Process: ??? [1]
Responsible: MyAppAgent [581]
User ID: 501
Date/Time: 2015-09-08 10:32:09.940 -0400
OS Version: Mac OS X 10.10.5 (14F27)
Crashed Thread: 3
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000022b0dd78
....
Thread 3 Crashed:
0 com.Mycmp.MyApp.MyAppAgent 0x00012a74 -[AppMainController sendPacketForLoginStatus] + 1644
1 com.Mycmp.MyApp.MyAppAgent 0x0001012c -[AppMainController timerQueryDiscovery:] + 1726
2 com.apple.Foundation 0x943ba76f __NSFireTimer + 119
3 com.apple.CoreFoundation 0x90653006 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22
4 com.apple.CoreFoundation 0x90652ab4 __CFRunLoopDoTimer + 1316
5 com.apple.CoreFoundation 0x906ce54f __CFRunLoopDoTimers + 351
6 com.apple.CoreFoundation 0x9060a531 __CFRunLoopRun + 2081
7 com.apple.CoreFoundation 0x90609aa6 CFRunLoopRunSpecific + 390
8 com.apple.CoreFoundation 0x9060990b CFRunLoopRunInMode + 123
9 com.apple.Foundation 0x944043ea -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 305
10 com.apple.Foundation 0x944847fa -[NSRunLoop(NSRunLoop) run] + 76
11 com.Mycmp.MyApp.MyAppAgent 0x00002ff0 -[AppMainController threadDiscovery:] + 360
12 com.apple.Foundation 0x943acb8d -[NSThread main] + 45
13 com.apple.Foundation 0x943ac936 __NSThread__main__ + 1538
14 libsystem_pthread.dylib 0x9abfcc25 _pthread_body + 138
15 libsystem_pthread.dylib 0x9abfcb9b _pthread_start + 162
16 libsystem_pthread.dylib 0x9abf9e32 thread_start + 34