I can’t understand a crash. - ios

Question

I got a crash from crashlytics. Probably it connected with weakSelf.
Crashed: com.apple.main-thread
EXC_BREAKPOINT 0x000000000defe
0 libobjc.A.dylib 0x224aea44 _objc_trap()
1 libobjc.A.dylib 0x224aeaa9 _objc_inform + 70
2 libobjc.A.dylib 0x224c8413 weak_register_no_lock + 210
3 libobjc.A.dylib 0x224c8993 objc_initWeak + 130
4 GPS_______appLite 0xd77b1 -[ModuleView observeValueForKeyPath:ofObject:change:context:] (ModuleView.m:232)
5 GPS_______appLite 0xd9287 -[ModuleSpeedometerView observeValueForKeyPath:ofObject:change:context:] (ModuleSpeedometerView.m:198)
6 Foundation 0x2349aa91 NSKVONotify + 52
7 Foundation 0x23479bef NSKeyValueNotifyObserver + 286
8 Foundation 0x23479847 NSKeyValueDidChange + 346
9 Foundation 0x23466599 -[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 96
10 GPS_______appLite 0x12c393 -[GPSTracker private_updateCurrentStatisticsWithLocation:] (GPSTracker.mm:1887)
11 GPS_______appLite 0x12c1b9 -[GPSTracker private_addLocationToHistory:] (GPSTracker.mm:1870)
12 GPS_______appLite 0x12c6af -[GPSTracker private_processNewLocation:fromManager:] (GPSTracker.mm:1938)
13 GPS_______appLite 0x12c88b -[GPSTracker locationManager:didUpdateLocations:] (GPSTracker.mm:1953)
14 CoreLocation 0x28c5c493 (null) + 25830
15 CoreLocation 0x28c5765b (null) + 5806
16 CoreLocation 0x28c50725 (null) + 988
17 CoreFoundation 0x22cd5d91 __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
18 CoreFoundation 0x22cd584d __CFRunLoopDoBlocks + 216
19 CoreFoundation 0x22cd41bf __CFRunLoopRun + 1806
20 CoreFoundation 0x22c232e9 CFRunLoopRunSpecific + 520
21 CoreFoundation 0x22c230d5 CFRunLoopRunInMode + 108
22 GraphicsServices 0x24213ac9 GSEventRunModal + 160
23 UIKit 0x272e80b9 UIApplicationMain + 144
24 GPS_______appLite 0x10adc7 main (main.m:15)
25 libdispatch.dylib 0x228cb873 (Missing)
and code
//ModuleView class
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
if ([object isKindOfClass:[GPSTracker class]])
{
__weak GPSTracker *tracker = (GPSTracker *)object;
__weak __typeof__(self) weakSelf = self;
dispatch_async(dispatch_get_main_queue(), ^{
if ([keyPath isEqualToString:NSStringFromSelector(#selector(trackerMode))])
{
[weakSelf trackerStateChanged];
}
else if ([keyPath isEqualToString:NSStringFromSelector(#selector(currentStatistics))])
{
id oldValue = [change objectForKey:NSKeyValueChangeOldKey];
if (!oldValue
|| [oldValue isKindOfClass:[NSNull class]])
{
// If statistics instance has been initialized
if (!weakSelf.shouldIgnoreUpdates)
{
[tracker.currentStatistics.time addUniqueObserver:weakSelf
forKeyPath:NSStringFromSelector(#selector(elapsed))
options:NSKeyValueObservingOptionNew];
}
}
[weakSelf trackerUpdate];
}
});
}
else if ([object isKindOfClass:[GPSTrackerTimeStatistics class]])
{
__weak __typeof__(self) weakSelf = self;
dispatch_async(dispatch_get_main_queue(), ^{
[weakSelf timerUpdate];
});
}
}

Answer 1

for released version you can see crashes and line of code,
in xCode : Window-> Organizer-> Crashes
and select app and version from left panels
try "Exception Breakpoint"
Exception Breakpoint automatically add breakpoint to line has cause crash, and you can see the problem
to add Exception Breakpoint:
in xCode :
top menu -> Debug -> Breakpoints -> Create Exception Breakpoint...
and run again