I&#39;m getting different kind of crash reports related to `VectorKit` and `MKMapSnapShotter`. Crashes occur pretty random, but it seems like they happen most when returning from the background. The device does not send out any memory warnings before it happens.

What&#39;s happening here?

I&#39;m using:
   
    if (!_snapshotQueue) {
        _snapshotQueue = dispatch_queue_create(&quot;com.bestappever.snapshot&quot;, DISPATCH_QUEUE_SERIAL);
    }
    [_snapshotter cancel]
    _snapshotter = [[MKMapSnapshotter alloc] initWithOptions:options];
    __weak __typeof(self)__self = self;
    [_snapshotter startWithQueue:queue completionHandler:^(MKMapSnapshot *snapshot, NSError *error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            __strong __typeof(__self)_self = __self;
            [_self doSomething];
        });
    }];

The most common one is as follows:

    Thread 11 Crashed:
	0   libobjc.A.dylib                      0x38502b66 objc_msgSend + 5
	1   VectorKit                            0x35bc8997 -[VKTileProvider changeTileForKey:toState:withMetadata:withTile:forLayer:] + 51
	2   VectorKit                            0x35c1f88d -[VKTileProvider tileSource:invalidateKeys:] + 168
	3   VectorKit                            0x35c41325 -[VKTileSource didFailToLoadTileKey:error:] + 196
	4   GeoServices                          0x32ca906b ___ZN8LoadItem15deleteRequesterEP8NSStringbb_block_invoke + 87
	5   libdispatch.dylib                    0x389ec0c3 _dispatch_call_block_and_release + 11
	6   libdispatch.dylib                    0x389f0e7b _dispatch_queue_drain + 375
	7   libdispatch.dylib                    0x389edf93 _dispatch_queue_invoke + 43
	8   libdispatch.dylib                    0x389f1745 _dispatch_root_queue_drain + 77
	9   libdispatch.dylib                    0x389f19c5 _dispatch_worker_thread2 + 57
	10  libsystem_pthread.dylib              0x38b1bdff _pthread_wqthread + 298
	11  libsystem_pthread.dylib              0x38b1bcc4 start_wqthread + 8


Some other examples:

    
	Thread 11 Crashed:
	0   libobjc.A.dylib                      0x3850a7aa lookUpImpOrForward + 94
	1   libobjc.A.dylib                      0x3850302b _class_lookupMethodAndLoadCache3 + 35
	2   libobjc.A.dylib                      0x38502df9 _objc_msgSend_uncached + 25
	3   VectorKit                            0x35bc8997 -[VKTileProvider changeTileForKey:toState:withMetadata:withTile:forLayer:] + 50
	4   VectorKit                            0x35bc895d -[VKTileProvider tileSource:didFetchTile:forKey:] + 60
	5   VectorKit                            0x35bc8915 -[VKTileSource fetchedTile:forKey:] + 44
	6   VectorKit                            0x35bc9a95 -[VKTileSetBackedTileSource fetchedTile:forKey:] + 212
	7   VectorKit                            0x35bc889d -[VKTileSource _fetchedTile:] + 224
	8   VectorKit                            0x35bc8409 __49-[VKTileSource decodeData:downloadKey:sourceKey:]_block_invoke_3 + 109
	9   libdispatch.dylib                    0x389ec0c3 _dispatch_call_block_and_release + 11
	10  libdispatch.dylib                    0x389f0e7b _dispatch_queue_drain + 375
	11  libdispatch.dylib                    0x389edf93 _dispatch_queue_invoke + 43
	12  libdispatch.dylib                    0x389f1745 _dispatch_root_queue_drain + 77
	13  libdispatch.dylib                    0x389f19c5 _dispatch_worker_thread2 + 57
	14  libsystem_pthread.dylib              0x38b1bdff _pthread_wqthread + 298
	15  libsystem_pthread.dylib              0x38b1bcc4 start_wqthread + 8


    Thread 6 Crashed:
	0   libsystem_kernel.dylib               0x390a41fc __pthread_kill + 8
	1   libsystem_c.dylib                    0x39054ffd abort + 76
	2   Ding Dong                            0x00090de7 uncaught_exception_handler + 27
	3   CoreFoundation                       0x2e6a524f __handleUncaughtException + 579
	4   libobjc.A.dylib                      0x38ae590f _objc_terminate() + 175
	5   libc++abi.dylib                      0x3839a1c7 std::__terminate(void (*)()) + 79
	6   libc++abi.dylib                      0x38399a1d __cxxabiv1::exception_cleanup_func(_Unwind_Reason_Code, _Unwind_Exception*) + 1
	7   libobjc.A.dylib                      0x38ae5783 objc_exception_throw + 250
	8   CoreFoundation                       0x2e6a88e7 -[NSObject doesNotRecognizeSelector:] + 202
	9   CoreFoundation                       0x2e6a71cb ___forwarding___ + 707
	10  CoreFoundation                       0x2e5f64d8 _CF_forwarding_prep_0 + 24
	11  VectorKit                            0x36077cb9 -[VKTileProvider tileSource:keyIsNeeded:] + 68
	12  VectorKit                            0x36077c2b -[VKTileSource _shouldDecodeTile:] + 178
	13  VectorKit                            0x36077a91 -[VKTileSource didFetchData:forKey:] + 108
	14  GeoServices                          0x3319a087 ___ZNK49-[GEOTileLoaderInternal _loadedTile:forKey:info:]66__49-[GEOTileLoaderInternal _loadedTile:forKey:info:]_block_invoke3$_1clERKN8LoadItem9RequesterE_block_invoke_2 + 55
	15  libdispatch.dylib                    0x38fc8d1b _dispatch_call_block_and_release + 11
	16  libdispatch.dylib                    0x38fcf273 _dispatch_queue_drain$VARIANT$mp + 375
	17  libdispatch.dylib                    0x38fcf06b _dispatch_queue_invoke$VARIANT$mp + 43
	18  libdispatch.dylib                    0x38fcfce1 _dispatch_root_queue_drain + 77
	19  libdispatch.dylib                    0x38fcff59 _dispatch_worker_thread2 + 57
	20  libsystem_pthread.dylib              0x3910adbf _pthread_wqthread + 298
	21  libsystem_pthread.dylib              0x3910ac84 start_wqthread + 8

    Thread 16 Crashed:
	0   VectorKit                            0x35a36476 std::__1::__hash_iterator&lt;std::__1::__hash_node&lt;std::__1::pair&lt;VKTileKey, void const*&gt;, void*&gt;*&gt; std::__1::__hash_table&lt;std::__1::pair&lt;VKTileKey, void const*&gt;, std::__1::__unordered_map_hasher&lt;VKTileKey, void const*, hashkey, true&gt;, std::__1::__unordered_map_equal&lt;VKTileKey, void const*, eqkey, true&gt;, vk_allocator&lt;std::__1::pair&lt;VKTileKey, void const*&gt; &gt; &gt;::find&lt;VKTileKey&gt;(VKTileKey const&amp;) + 54
	1   VectorKit                            0x35a3642d -[VKTileKeyMap objectForKey:] + 24
	2   VectorKit                            0x35a3a837 -[VKTileKeyList containsKey:] + 34
	3   VectorKit                            0x35a54b9f -[VKTileProvider tileMatters:] + 78
	4   VectorKit                            0x35a549c1 -[VKTileProvider changeTileForKey:toState:withMetadata:withTile:forLayer:] + 92
	5   VectorKit                            0x35a5495d -[VKTileProvider tileSource:didFetchTile:forKey:] + 60
	6   VectorKit                            0x35a54915 -[VKTileSource fetchedTile:forKey:] + 44
	7   VectorKit                            0x35a5489d -[VKTileSource _fetchedTile:] + 224
	8   VectorKit                            0x35a54409 __49-[VKTileSource decodeData:downloadKey:sourceKey:]_block_invoke_3 + 109
	9   libdispatch.dylib                    0x388780c3 _dispatch_call_block_and_release + 11
	10  libdispatch.dylib                    0x3887ce7b _dispatch_queue_drain + 375
	11  libdispatch.dylib                    0x38879f93 _dispatch_queue_invoke + 43
	12  libdispatch.dylib                    0x3887d745 _dispatch_root_queue_drain + 77
	13  libdispatch.dylib                    0x3887d9c5 _dispatch_worker_thread2 + 57
	14  libsystem_pthread.dylib              0x389a7dff _pthread_wqthread + 298
	15  libsystem_pthread.dylib              0x389a7cc4 start_wqthread + 8

All Mkmapsnapshotter Solutions on Gang of Coders

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VectorKit crash reports with MKMapSnapshotter on iOS