Crashed: com.apple.coreanimation.imageprovider.concurrent
0  libsystem_platform.dylib       0x23bc os_unfair_lock_lock + 12
1  CoreGraphics                   0xf2540 CGPDFPagePurgeResources + 36
2  CoreGraphics                   0xcc008 CGContextDrawPDFPageWithDrawingCallbacks + 860
3  CoreGraphics                   0xf2a98 CGContextDrawPDFPageWithProgressCallback + 36
4  CorePDF                        0x6e554 -[UIPDFPageContentDelegate drawLayer:inContext:] + 364
5  QuartzCore                     0x19586c tiled_layer_render(_CAImageProvider*, unsigned int, unsigned int, unsigned int, unsigned int, void*) + 1368
6  QuartzCore                     0x23d3b4 CAImageProviderThread(unsigned int*, bool) + 996
7  libdispatch.dylib              0x3fdc _dispatch_client_callout + 20
8  libdispatch.dylib              0x746c _dispatch_continuation_pop + 504
9  libdispatch.dylib              0x6ad4 _dispatch_async_redirect_invoke + 584
10 libdispatch.dylib              0x15a6c _dispatch_root_queue_drain + 396
11 libdispatch.dylib              0x16284 _dispatch_worker_thread2 + 164
12 libsystem_pthread.dylib        0xdbc _pthread_wqthread + 228
13 libsystem_pthread.dylib        0xb98 start_wqthread + 8