What steps will reproduce the problem? Please provide a link to a
demonstration page if at all possible, or attach code.
1. Enable CoreData concurrency debugging: add `-com.apple.CoreData.ConcurrencyDebug 1` to Scheme arguments
2. Open a map view
3. The map begins to render then the app crashes with:

* thread #10: tid = 0x72c1c, 0x0000000108fd9124 CoreData`+[NSManagedObjectContext __Multithreading_Violation_AllThatIsLeftToUsIsHonor__] + 4, queue = 'SQLQueue 0x7fe39060a0f0 for Objects.sqlite', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
* frame #0: 0x0000000108fd9124 CoreData`+[NSManagedObjectContext __Multithreading_Violation_AllThatIsLeftToUsIsHonor__] + 4
frame #1: 0x0000000108fd9525 CoreData`_PFAssertSafeMultiThreadedAccess_impl + 645
frame #2: 0x0000000108f597a8 CoreData`-[NSManagedObjectContext objectRegisteredForID:] + 328
frame #3: 0x0000000109057d99 CoreData`-[NSSQLiteConnection updateRow:forRequestContext:] + 169
frame #4: 0x00000001090fdaab CoreData`_writeChangesForSaveRequest + 1579
frame #5: 0x00000001090ff433 CoreData`_executeSaveChangesRequest + 291
frame #6: 0x0000000108f8e9c6 CoreData`-[NSSQLSaveChangesRequestContext executeRequestUsingConnection:] + 38
frame #7: 0x00000001090a4eb7 CoreData`__52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 215
frame #8: 0x000000010eaa50cd libdispatch.dylib`_dispatch_client_callout + 8
frame #9: 0x000000010ea8230a libdispatch.dylib`_dispatch_barrier_sync_f_invoke + 340
frame #10: 0x00000001090a4d8c CoreData`-[NSSQLDefaultConnectionManager handleStoreRequest:] + 236
frame #11: 0x00000001090ac61f CoreData`-[NSSQLCoreDispatchManager routeStoreRequest:] + 351
frame #12: 0x000000010902f7d9 CoreData`-[NSSQLCore dispatchRequest:withRetries:] + 233
frame #13: 0x000000010902a89f CoreData`-[NSSQLCore processSaveChanges:forContext:] + 191
frame #14: 0x0000000108f21e4d CoreData`-[NSSQLCore executeRequest:withContext:error:] + 909
frame #15: 0x00000001090155d9 CoreData`__65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke + 4169
frame #16: 0x000000010900d966 CoreData`-[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 390
frame #17: 0x0000000108f2187e CoreData`-[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 654
frame #18: 0x0000000108f4baba CoreData`-[NSManagedObjectContext save:] + 3658
frame #19: 0x00000001079f92b8 Wingtip`__72-[GMSObjectDataCache storeObjectNamesAndData:version:completionHandler:]_block_invoke + 400
frame #20: 0x000000010ea7b980 libdispatch.dylib`_dispatch_call_block_and_release + 12
frame #21: 0x000000010eaa50cd libdispatch.dylib`_dispatch_client_callout + 8
frame #22: 0x000000010ea82fb8 libdispatch.dylib`_dispatch_queue_serial_drain + 569
frame #23: 0x000000010ea83b9f libdispatch.dylib`_dispatch_queue_invoke + 1073
frame #24: 0x000000010ea8407f libdispatch.dylib`_dispatch_queue_override_invoke + 683
frame #25: 0x000000010ea863b7 libdispatch.dylib`_dispatch_root_queue_drain + 720
frame #26: 0x000000010ea8608b libdispatch.dylib`_dispatch_worker_thread3 + 123
frame #27: 0x000000010ee54746 libsystem_pthread.dylib`_pthread_wqthread + 1299
frame #28: 0x000000010ee54221 libsystem_pthread.dylib`start_wqthread + 13

It looks like [GMSObjectDataCache storeObjectNamesAndData:version:completionHandler:] is accessing an NSManagedObjectContext from an incorrect thread.

Operating system version: iOS 10.0
Google Maps SDK for iOS version: 2.1.0
Hardware model: iOS Simulator iPhone 7

*********************************************************
For developers viewing this issue: please click the 'star' icon to be
notified of future changes, and to let us know how many of you are
interested in seeing it resolved.
*********************************************************