It seems the comment does not support markdown, I will reply below. ~~It was still failed. In fact the original issue was exactly SecKeychainCopyDefault failed when I run xcodebuild test. However, if I ran default-keychain directly in the terminal, it can correctly return the default keychain. Therefore, I'm thinking if that is an issue with xcode setup on the CI host. Would I need to do a code-sign for xcode build? ~~

I will follow up with Github runner image to see if there is further suggestions. Thank you!

Thanks, I will try the memory debug tools. I tried DISPATCH_DATA_DESTRUCTOR_DEFAULT, but, it was the same issue. According to the doc, DISPATCH_DATA_DESTRUCTOR_DEFAULT should create a copy of the "message_ptr". In this case, I would assume the memory in data should not be corrupted? I will focus more on nw_connection related changes then.

Thanks!!

That's good to know. I've been testing against XCode debugger... I guess I need to start over in that case (T_T). Thank you!