Modifications to the layout engine must not be performed from a background thread after it has been accessed from the main thread. `Triggered by Thread: 36 Last Exception Backtrace: 0 CoreFoundation 0x1a1585e88 __exceptionPreprocess + 164 (NSException.m:202) 1 libobjc.A.dylib 0x19a8bf8d8 objc_exception_throw + 60 (objc-exception.mm:356) 2 CoreAutoLayout 0x1bde18e84 _AssertAutoLayoutOnAllowedThreadsOnly + 328 (NSISEngine.m:0) 3 CoreAutoLayout 0x1bde0f9b4 -[NSISEngine _optimizeWithoutRebuilding] + 72 (NSISEngine.m:1709) 4 CoreAutoLayout 0x1bde0f8e4 -[NSISEngine optimize] + 96 (NSISEngine.m:1683) 5 CoreAutoLayout 0x1bde0f670 -[NSISEngine performPendingChangeNotifications] + 104 (NSISEngine.m:677) 6 UIKitCore 0x1a373fa44 -[UIView(Hierarchy) layoutSubviews] + 128 (UIView.m:13091) 7 UIKitCore 0x1a373e020 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1980 (UIView.m:18554) 8 QuartzCore 0x1a2c139ec CA::Layer::layout_if_needed(CA::Transaction*) + 500 (CALayer.mm:10226) 9 QuartzCore 0x1a2c270a0 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 148 (CALayer.mm:2516) 10 QuartzCore 0x1a2c385b0 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 456 (CAContextInternal.mm:2708) 11 QuartzCore 0x1a2c6d5ec CA::Transaction::commit() + 652 (CATransactionInternal.mm:431) 12 QuartzCore 0x1a2cbdab4 CA::Transaction::release_thread(void*) + 228 (CATransactionInternal.mm:634) 13 libsystem_pthread.dylib 0x1ee5dcbd8 _pthread_tsd_cleanup + 620 (pthread_tsd.c:300) 14 libsystem_pthread.dylib 0x1ee5df674 _pthread_exit + 84 (pthread.c:1719) 15 libsystem_pthread.dylib 0x1ee5dc0e0 _pthread_wqthread_exit + 76 (pthread.c:2578) 16 libsystem_pthread.dylib 0x1ee5dbe80 _pthread_wqthread + 424 (pthread.c:2612) 17 libsystem_pthread.dylib 0x1ee5dbb98 start_wqthread + 8 (:-1) Thread 36 Crashed: 0 libsystem_c.dylib 0x00000001a8c11404 __abort + 160 (abort.c:167) 1 libsystem_c.dylib 0x00000001a8bb9c98 abort + 192 (abort.c:126) 2 libc++abi.dylib 0x00000001ee522b8c abort_message + 132 (abort_message.cpp:78) 3 libc++abi.dylib 0x00000001ee512a80 demangling_terminate_handler() + 336 (cxa_default_handlers.cpp:71) 4 libobjc.A.dylib 0x000000019a8c5d3c _objc_terminate() + 144 (objc-exception.mm:498) 5 SansiroLive 0x0000000104fa4f7c BLYCPPExceptionTerminate() + 2044 6 libc++abi.dylib 0x00000001ee521f28 std::__terminate(void ()()) + 20 (cxa_handlers.cpp:59) 7 libc++abi.dylib 0x00000001ee524c2c __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception) + 36 (cxa_exception.cpp:152) 8 libc++abi.dylib 0x00000001ee524bd8 __cxa_throw + 140 (cxa_exception.cpp:283) 9 libobjc.A.dylib 0x000000019a8bfa38 objc_exception_throw + 412 (objc-exception.mm:385) 10 CoreAutoLayout 0x00000001bde18e84 _AssertAutoLayoutOnAllowedThreadsOnly + 328 (NSISEngine.m:0) 11 CoreAutoLayout 0x00000001bde0f9b4 -[NSISEngine _optimizeWithoutRebuilding] + 72 (NSISEngine.m:1709) 12 CoreAutoLayout 0x00000001bde0f8e4 -[NSISEngine optimize] + 96 (NSISEngine.m:1683) 13 CoreAutoLayout 0x00000001bde0f670 -[NSISEngine performPendingChangeNotifications] + 104 (NSISEngine.m:677) 14 UIKitCore 0x00000001a373fa44 -[UIView(Hierarchy) layoutSubviews] + 128 (UIView.m:13091) 15 UIKitCore 0x00000001a373e020 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1980 (UIView.m:18554) 16 QuartzCore 0x00000001a2c139ec CA::Layer::layout_if_needed(CA::Transaction*) + 500 (CALayer.mm:10226) 17 QuartzCore 0x00000001a2c270a0 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 148 (CALayer.mm:2516) 18 QuartzCore 0x00000001a2c385b0 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 456 (CAContextInternal.mm:2708) 19 QuartzCore 0x00000001a2c6d5ec CA::Transaction::commit() + 652 (CATransactionInternal.mm:431) 20 QuartzCore 0x00000001a2cbdab4 CA::Transaction::release_thread(void*) + 228 (CATransactionInternal.mm:634) 21 libsystem_pthread.dylib 0x00000001ee5dcbd8 _pthread_tsd_cleanup + 620 (pthread_tsd.c:300) 22 libsystem_pthread.dylib 0x00000001ee5df674 _pthread_exit + 84 (pthread.c:1719) 23 libsystem_pthread.dylib 0x00000001ee5dc0e0 _pthread_wqthread_exit + 76 (pthread.c:2578) 24 libsystem_pthread.dylib 0x00000001ee5dbe80 _pthread_wqthread + 424 (pthread.c:2612) 25 libsystem_pthread.dylib 0x00000001ee5dbb98 start_wqthread + 8 (:-1) `