Crash llibobjc.A.dylib objc_release + 36 - ios

Question

I use crashlytics to get the crashes of my app, i am currently Crashlytics version: 3.9.3. Some users are getting a crash that I cannot seem to repro on my machine. This is the logs from Fabric:
Crashed: com.apple.root.default-qos
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x00004a4b9a43bec8
#37. Crashed: com.apple.root.default-qos
0 libobjc.A.dylib 0x7fff6b43d184 objc_release + 36
1 MyApp 0x10805ad2d __66-[AppManager getCountriesDelegate:]_block_invoke (AppManager.m:1412)
2 libdispatch.dylib 0x7fff6c006591 _dispatch_call_block_and_release + 12
3 libdispatch.dylib 0x7fff6bffed50 _dispatch_client_callout + 8
4 libdispatch.dylib 0x7fff6c00bc61 _dispatch_queue_override_invoke + 880
5 libdispatch.dylib 0x7fff6c000941 _dispatch_root_queue_drain + 515
6 libdispatch.dylib 0x7fff6c0006ed _dispatch_worker_thread3 + 101
7 libsystem_pthread.dylib 0x7fff6c2c31ca _pthread_wqthread + 1387
8 libsystem_pthread.dylib 0x7fff6c2c2c4d start_wqthread + 13
- (void) getCountriesDelegate:(id<AppManagerDelegate>)delegate
{
__weak __typeof(id<AppManagerDelegate>) weakDelegate = delegate;
__weak __typeof(self) weakSelf = self;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ //my function definition
});

Answer 1

There are multiples reasons why you can get a EXC_BAD_ACCESS KERN_INVALID_ADDRESS error code. Appel's documentation says:
EXC_BAD_ACCESS/KERN_INVALID_ADDRESS — This is caused by the thread
accessing unmapped memory. It may be triggered by either a data access
or an instruction fetch; the Thread State section describes how to
tell the difference.
You should look deeply at your class AppManager. As the crashlog said's the crash occurs at line 1412 of file AppManager.m in the method getCountriesWithRespectToPurposeAndFavoriteDelegate:.