Objective c dispatch_async crash - objective-c

Question

code :
- (void)stopCurrentSessionFromSuite:(NSNotification*)notification{
isCloseCurrentSession = YES;
dispatch_async(self.dataSendingQueue, ^{
CARD8 messageToDisableSession = rpcHostDisableMsg;
[readerNwriter writeExact:(char*)&messageToDisableSession ofLenght:sizeof(CARD8) secApplied:NO];
});
[rpcCaptureMgr stopCaptureSession];
}
Crash :
Time Awake Since Boot: 1400 seconds
System Integrity Protection: enabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes:
KERN_INVALID_ADDRESS at 0x0000000000000070 Exception Note:
EXC_CORPSE_NOTIFY
Termination Signal: Segmentation fault: 11 Termination Reason:
Namespace SIGNAL, Code 0xb Terminating Process: exc handler [0]
VM Regions Near 0x70:
-->
__TEXT 000000010871a000-000000010873a000 [ 128K] r-x/rwx SM=COW
/Applications/RemotePCSuite/*/RemotePCDesktop.app/Contents/MacOS/RemotePCDesktop
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0
libdispatch.dylib 0x00007fff72de50db
_dispatch_continuation_async + 5 1 com.prosoftnet.remotepcDesktop 0x0000000108727fd5
-[RPCDesktopAppDelegate stopCurrentSessionFromSuite:] + 104 2 com.apple.CoreFoundation 0x00007fff4b7a333c
CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER + 12 3 com.apple.CoreFoundation 0x00007fff4b7a32cf
_CFXRegistrationPost_block_invoke + 63 4 com.apple.CoreFoundation 0x00007fff4b7ab92c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK + 12 5
com.apple.CoreFoundation 0x00007fff4b78e8a3 __CFRunLoopDoBlocks
+ 275 6 com.apple.CoreFoundation 0x00007fff4b78e668 __CFRunLoopRun + 3128 7 com.apple.CoreFoundation 0x00007fff4b78d797 CFRunLoopRunSpecific + 487 8 com.apple.HIToolbox
0x00007fff4aaa2866 RunCurrentEventLoopInMode + 286 9
com.apple.HIToolbox 0x00007fff4aaa25d6
ReceiveNextEventCommon + 613 10 com.apple.HIToolbox
0x00007fff4aaa2354 _BlockUntilNextEventMatchingListInModeWithFilter +
64 11 com.apple.AppKit 0x00007fff48d9fa23 _DPSNextEvent
+ 2085 12 com.apple.AppKit 0x00007fff49534e6c -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 3044 13 com.apple.AppKit 0x00007fff48d94831 -[NSApplication run]
+ 764 14 com.apple.AppKit 0x00007fff48d639d2 NSApplicationMain + 804 15 libdyld.dylib
0x00007fff72e0c145 start + 1