Details
P2: Important Description
xCode 9 introduced a new tool which checks UI thread access: https://developer.apple.com/documentation/code_diagnostics/main_thread_checker.
When starting a Qt project from xCode then the checker outputs several warnings like this:
2017-10-17 08:12:12.482151+0200 mapproblem[306:9393] [DYMTLInitPlatform] platform initialization successful JIT is disabled for QML. Property bindings and animations will be very slow. Visit https://wiki.qt.io/V4 to learn about possible solutions for your platform. stale focus object QObject(0x0) , doing manual update 2017-10-17 08:12:13.701932+0200 mapproblem[306:9182] refreshPreferences: HangTracerEnabled: 0 2017-10-17 08:12:13.702360+0200 mapproblem[306:9182] refreshPreferences: HangTracerDuration: 500 2017-10-17 08:12:13.702647+0200 mapproblem[306:9182] refreshPreferences: ActivationLoggingEnabled: 0 ActivationLoggingTaskedOffByDA:0 ================================================================= Main Thread Checker: UI API called on a background thread: -[UIView layer] PID: 306, TID: 9433, Thread name: QSGRenderThread, Queue name: com.apple.root.default-qos.overcommit, QoS: 21 Backtrace: 4 mapproblem 0x0000000100d3628c _ZNK10QIOSWindow9eaglLayerEv + 48 5 mapproblem 0x0000000100d3ed64 _ZNK11QIOSContext23needsRenderbufferResizeEP16QPlatformSurface + 152 6 mapproblem 0x0000000100d3e860 _ZN11QIOSContext11makeCurrentEP16QPlatformSurface + 740 7 mapproblem 0x0000000100d3f074 _ZThn16_N11QIOSContext11makeCurrentEP16QPlatformSurface + 36 8 mapproblem 0x00000001018ab6b0 _ZN14QOpenGLContext11makeCurrentEP8QSurface + 488 9 mapproblem 0x000000010123b6a8 _ZN15QSGRenderThread3runEv + 408 10 mapproblem 0x0000000101d4606c _ZN14QThreadPrivate5startEPv + 788 11 libsystem_pthread.dylib 0x000000018498032c <redacted> + 308 12 libsystem_pthread.dylib 0x00000001849801f8 <redacted> + 0 13 libsystem_pthread.dylib 0x000000018497ec38 thread_start + 4