Our iOS app, which was working normally on Xcode 13.4.1, now has an exception at startup under Xcode 14.0.1.

Thread 1: EXC_BAD_ACCESS (code=1, address=0x1176aca60)

But this is only visible when debugging; if I run it directly on device, it appears to run fine. Still a problem because we cannot debug our app.

There is very little information available, but this is the call stack, none of which is our code. I stepped through a lot of our startup code without noticing any problems.

Thread 1 Queue : com.apple.main-thread (serial)
#0 0x0000000183aa3518 in objc_release ()
#1 0x0000000183aa15d8 in AutoreleasePoolPage::releaseUntil(objc_object**) ()
#2 0x0000000183aa4f40 in objc_autoreleasePoolPop ()
#3 0x00000001a0061aec in -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:] ()
#4 0x00000001a009cd3c in __92-[FBSWorkspaceScenesClient createSceneWithIdentity:parameters:transitionContext:completion:]_block_invoke ()
#5 0x000000010900e04c in _dispatch_client_callout ()
#6 0x0000000109011ac8 in _dispatch_block_invoke_direct ()
#7 0x00000001a006bf2c in FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK ()
#8 0x00000001a006bac8 in -[FBSSerialQueue _targetQueue_performNextIfPossible] ()
#9 0x00000001a006e2a8 in -[FBSSerialQueue _performNextFromRunLoopSource] ()
#10 0x000000018a7be22c in CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION ()
#11 0x000000018a7ca614 in __CFRunLoopDoSource0 ()
#12 0x000000018a74e57c in __CFRunLoopDoSources0 ()
#13 0x000000018a763eb8 in __CFRunLoopRun ()
#14 0x000000018a7691e4 in CFRunLoopRunSpecific ()
#15 0x00000001c3589368 in GSEventRunModal ()
#16 0x000000018cc18d88 in -[UIApplication _run] ()
#17 0x000000018cc189ec in UIApplicationMain ()
#18 0x0000000101d76580 in main at /Users/aaronl/engine-johnsonville/src/platform/ios/main.mm:8
#19 0x00000001a8a8d948 in start ()

Turning on some Xcode debug flags showed the following message:

2022-10-13 16:33:49.020927 1300 umajin_viewer[1297:357539] *** -[CaptureMTLCaptureScope release]: message sent to deallocated instance 0x280aafb40

The app is a combination of Objective-C and C , and has Vulkan graphics rendering on top of Metal. All this was working well up till now.

I'm looking for any clues on how to find out what is going wrong!

CodePudding user response：

Eventually we were able to confirm that this was a problem in MoltenVK, the implementation of Vulkan on top of Metal for iOS and Mac. It was releasing something that Apple expects to be autoreleased (MTLCaptureScope)? Because it wasn't our code we couldn't see into it. Upgrading to the latest solved this.