Xcode has had the ability to debug app extensions for many years. However, several years ago it used to be so bad as to be unusable (extremely slow to load, very slow to run, and just utterly utterly unreliable).
I'm glad to say this situation changed and for the past few years its been great, interactively running app extension with Xcode 14.2 or 14.3 is as stable and almost as quick as interacting with the main app.
But unfortunately there's been a big step back in reliability in Xcode 15.
Many times with Xcode 15 it just stops working, its just not possible to step into the code, stop at a breakpoint for app extensions.
It's not like this all the time, sometimes it works just fine, but the problem is quite often it just stops working (by not working I mean breakpoints set in an app extension aren't hit, despite the path of control going through them and the extension being selected as the scheme to execute)
The problem is once it stops working there's no way I've found to get it working again, restarting XCOde, rebuilding, restarting the phone, none of this works. Once Xcode has decided to stop working for debugging app extensions there's no apparent way to get it going again. It doesn't matter what type of extension it is - action extension, unwanted communication extension, notification service extension, ..... There's just something fundamentally regressed in XCode 15 that didn't exist with Xcode 14.
Apple please can you investigate fixing this, it makes developing and debugging app extension impossible. At least are there any tips to try to attempt to reset Xcode to try and get it working again once its stopped interactively running the extensions?