在过去的几个月里，我们的应用程序中随机出现了这些错误，它们出现在 Bugsnag 中。它们肯定会导致崩溃，因为我们团队的内部成员报告了崩溃，但随后无法重现它们。这是一个完整的跟踪：
EXC_BAD_ACCESS Attempted to dereference garbage pointer 0x167f4beb8.
/usr/lib/libobjc.A.dylib objc_msgSend
Frameworks/Foundation.framework/Foundation -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:usingBlock:]
Frameworks/Foundation.framework/Foundation -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:]
Frameworks/Foundation.framework/Foundation -[NSOperationQueue setMaxConcurrentOperationCount:]
GreatJonesStreet-Prod mh_execute_header
GreatJonesStreet-Prod mh_execute_header
GreatJonesStreet-Prod mh_execute_header
/usr/lib/system/libdispatch.dylib __dispatch_call_block_and_release
/usr/lib/system/libdispatch.dylib __dispatch_client_callout
/usr/lib/system/libdispatch.dylib __dispatch_queue_override_invoke
/usr/lib/system/libdispatch.dylib __dispatch_root_queue_drain
/usr/lib/system/libdispatch.dylib __dispatch_worker_thread3
/usr/lib/system/libsystem_pthread.dylib __pthread_wqthread
我在多个地方读到过其他人也遇到了这个问题，而 Bugsnag（这太讽刺了）似乎是在发现它的地方提到的常见问题。我并不是说 Bugsnag 导致了这个问题，但人们不断报告他们在 Bugsnag 报告中看到了崩溃日志。只是看起来奇怪的巧合。
这是另一个：
EXC_BAD_ACCESS Attempted to dereference garbage pointer 0xa8a94beb8.
/usr/lib/libobjc.A.dylib objc_msgSend
Frameworks/Foundation.framework/Foundation -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:usingBlock:]
Frameworks/Foundation.framework/Foundation -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:]
Frameworks/Foundation.framework/Foundation -[NSOperationQueue setMaxConcurrentOperationCount:]
GreatJonesStreet mh_execute_header
GreatJonesStreet mh_execute_header
GreatJonesStreet mh_execute_header
/usr/lib/system/libdispatch.dylib __dispatch_call_block_and_release
/usr/lib/system/libdispatch.dylib __dispatch_client_callout
/usr/lib/system/libdispatch.dylib __dispatch_queue_override_invoke
/usr/lib/system/libdispatch.dylib __dispatch_root_queue_drain
/usr/lib/system/libdispatch.dylib __dispatch_worker_thread3
/usr/lib/system/libsystem_pthread.dylib __pthread_wqthread
在发布此问题时，我们的 56 位用户发生了上述 75 个错误。
有人有想法么？？？