bool _WebTryThreadLock(bool), 0xa871560: Multiple locks on web thread not allowed! Please file a bug. Crashing now

bool _WebTryThreadLock(bool), 0xa871560: Multiple locks on web thread not
allowed! Please file a bug. Crashing now

I get Following bad access error when i try to push one of my view
controller and its random error sometime it comes and sometime it not
there is one class in which i use CFRunLoopRun(); ones i push that push
that class then only this error comes and still its not fixed let me show
you code where i have used CFRunLoopRun(); if i am doing something wrong
bool _WebTryThreadLock(bool), 0xa871560: Multiple locks on web thread not
allowed! Please file a bug. Crashing now...
1 0x5068c88 WebRunLoopLock(__CFRunLoopObserver*, unsigned long, void*)
2 0x2eb6afe __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
3 0x2eb6a3d __CFRunLoopDoObservers
4 0x2e94704 __CFRunLoopRun
5 0x2e93f44 CFRunLoopRunSpecific
6 0x2e93e1b CFRunLoopRunInMode
7 0x5068c50 RunWebThread(void*)
8 0x9465a5b7 _pthread_start
9 0x94644d4e thread_start
[self fatchAllEvent];
CFRunLoopRun(); // i want to wait until above method get executed
-(void)fatchAllEvent{
events = [[NSMutableArray alloc]init];
eventStore = [[EKEventStore alloc] init];
if ([eventStore
respondsToSelector:@selector(requestAccessToEntityType:completion:)])
{
[eventStore requestAccessToEntityType:EKEntityTypeEvent
completion:^(BOOL granted, NSError *error)
{
if (granted)
{
[self performSelectorOnMainThread:@selector(waitAsItoldYou)
withObject:nil
waitUntilDone:YES];
CFRunLoopStop(CFRunLoopGetMain());
// NSLog(@"LOOP has STOP");
}
}];
}
}
everything works perfectly but something this error comes dont know what
to do have checked some other people answer but nothing helped