I and one of my clients have found it impossible to use the 'capture view hierarchy' option in Xcode when running a debug version of an app using MetalAngle. The option was accessed via the menu option Debug -> View Debugging -> Capture View Hierarchy while the app was running on an iPhone. My client informs me that 'capture view hierarchy' works when using GLKit instead of MetalAngle.

After a delay of about 15 seconds the following message appeared in Xcode:

"[application name]" did not respond to the debugger's request for a view hierarchy snapshot. Please try again once the process becomes responsive. You can also investigate why the process is unresponsive by profiling it with the "Time Profiler" instrument.

A message also appears in the lldb debugger pane:

warning: Module "/Users/grahamasher/Library/Developer/Xcode/iOS DeviceSupport/iPhone12,3 17.1.2 (21B101)/Symbols/usr/lib/libobjc.A.dylib" uses triple "arm64e-apple-ios17.1.0", which is not compatible with the target triple "arm64-apple-ios9.3.0". Enabling per-module Swift scratch context.

I doubt that is relevant, but I include it in the interests of completeness.

I am using the latest release of MetalAngle: https://github.com/kakashidinho/metalangle/releases/tag/gles3-0.0.8.

The app does not crash when this problem occurs, but pauses as if a breakpoint has been hit. It runs normally if the menu command Debug -> Continue is used.