@eskimo Agree 100% with all your comments. Due to backwards compatibility on iOS/macOS (support for pre Network.framework devices) and due to multiplaform nature of my apps I implement Happy Eyeballs myself, but sooner or later I shall move to NWConnection… that is for sure!

I do not actually remember, but I would assume yes it worked - profiling the Catalyst variant, but I may not remember correctly. The screenshots above should indicate that my setup in code actually does work when used on iOS device. But my other tests confirm, that simply profiling a simple XCTestCase that uses os_signpost on macOS does not work either... So I believe it's not about catalyst, it's a general problem of profiling os_signpost from Xcode on the same Mac.

Deferred recording mode does not work either. Filed a bug FB13683303.

Can confirm, macOS Sonoma 14.5 + Xcode 15.4 works again. Thanks a lot!