when app enter background,sometimes crash at BSXPCCnx:com.apple.backboard.hid-services.xpc (BSCnx:client:BKHIDEventDeliveryManager)
this is crash stack: 0 libsystem_pthread.dylib 0x3b30 pthread_mutex_lock + 12 1 ilink_live 0xbd884 (缺少 UUID 973fe6c5058c35bda98679b0c8aa0129) 2 ilink_live 0xb75fc (缺少 UUID 973fe6c5058c35bda98679b0c8aa0129) 3 libsystem_c.dylib 0x23d68 __cxa_finalize_ranges + 492 4 libsystem_c.dylib 0x23b64 exit + 32 5 BackBoardServices 0x579ec -[BKSHIDEventDeliveryManager _initForTestingWithService:] + 98 6 BoardServices 0xbae8 __31-[BSServiceConnection activate]_block_invoke.182 + 128 7 BoardServices 0x17620 __61-[BSXPCServiceConnectionEventHandler _connectionInvalidated:]_block_invoke + 196 8 BoardServices 0x8f64 BSXPCServiceConnectionExecuteCallOut + 240 9 BoardServices 0x18e5c -[BSXPCServiceConnectionEventHandler _connectionInvalidated:] + 180 10 libdispatch.dylib 0x2370 _dispatch_call_block_and_release + 32 11 libdispatch.dylib 0x40d0 _dispatch_client_callout + 20 12 libdispatch.dylib 0xb6d8 _dispatch_lane_serial_drain + 744 13 libdispatch.dylib 0xc214 _dispatch_lane_invoke + 432 14 libdispatch.dylib 0x17258 _dispatch_root_queue_drain_deferred_wlh + 288 15 libdispatch.dylib 0x16aa4 _dispatch_workloop_worker_thread + 540 16 libsystem_pthread.dylib 0x4c7c _pthread_wqthread + 288 17 libsystem_pthread.dylib 0x1488 start_wqthread + 8
when crash happened ,most of time app recieved CBManagerStateResetting and CBManagerStateUnsupported event
