So it turns out there was probably a bug in the past that when you were adding a Swift file it would add/ask a Bridging header, but it wouldn’t add that line to your project
SWIFT_OPTIMIZATION_LEVEL = "-Onone";
which means you’d stay in this state
error: <EXPR>:1:1: error: use of unresolved identifier!
I could only find that out because I moved around files in my project and when I added ObjC files to the project, it asked me about a Bridging header (although I had one already!) and luckily added that
SWIFT_OPTIMIZATION_LEVEL. One could consider this is a bug to consider the default value is
fastest, but then again I guess this was only a bug in the past and got fixed now.
Still, I fixed now it might be a bug the other way around, if it add
none in the release build. I can’t test this right now because for testing this I only had a
Debug build. I’ll leave that as an exercise 🙂 for Apple’s Engineers.