my app crashed on iOS 12 only. this is the message, anyone help me , thanks.
Crashed: com.apple.coremedia.player.async.0x2856cf180
0 QuartzCore 0x1beb61578 X::Ref<CA::Shape>::operator=(CA::Shape*) + 20
1 QuartzCore 0x1beb61434 CABackingStoreGetFrontTexture(CABackingStore*, CGColorSpace*) + 348
2 QuartzCore 0x1beb612a8 CABackingStoreRetainFrontTexture + 48
3 QuartzCore 0x1bec88e54 -[CALayer(CALayerPrivate) _copyRenderLayer:layerFlags:commitFlags:] + 676
4 QuartzCore 0x1bec8e9e4 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 448
5 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
6 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
7 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
8 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
9 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
10 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
11 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
12 QuartzCore 0x1bec8e928 CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 260
13 QuartzCore 0x1bebe2528 CA::Context::commit_transaction(CA::Transaction*) + 3240
14 QuartzCore 0x1bec102f4 CA::Transaction::commit() + 608
15 MediaToolbox 0x1bf1012b0 remoteXPCPlayer_setClientVideoLayerArray + 1284
16 MediaToolbox 0x1bf100548 remoteXPCPlayer_SetProperty + 340
17 MediaToolbox 0x1bf0675dc playerasync_runOneCommand + 1876
18 MediaToolbox 0x1bf06a380 playerasync_runAsynchronousCommandOnQueue + 172
19 libdispatch.dylib 0x1ba0d4484 _dispatch_client_callout + 16
20 libdispatch.dylib 0x1ba0aefb0 _dispatch_lane_serial_drain$VARIANT$armv81 + 548
21 libdispatch.dylib 0x1ba0afb2c _dispatch_lane_invoke$VARIANT$armv81 + 468
22 libdispatch.dylib 0x1ba0b6afc _dispatch_root_queue_drain + 344
23 libdispatch.dylib 0x1ba0b68a8 _dispatch_worker_thread + 276
24 libsystem_pthread.dylib 0x1ba2b52fc _pthread_body + 128
25 libsystem_pthread.dylib 0x1ba2b525c _pthread_start + 48
26 libsystem_pthread.dylib 0x1ba2b8d08 thread_start + 4
the detail message here: http://crashes.to/s/5390fe23bcc