Xcode doesn't write anything to output console

Question

I am working on an iPhone/iPad app. All of a sudden output console stopped displaying ANY messages AT ALL. I tried to open older project - works just fine. So I thought that

Answer 1

Xcode 10.1 targeting iOS 11, Xcode stopped displaying console output from one build to another minutes later.

I have OS_ACTIVITY_MODE as an environment variable in my scheme and I get no output in the console in Xcode.

If I disable or remove OS_ACTIVITY_MODE from my scheme my log appears in the console - alas with a lot of system logging as well.

Try disabling OS_ACTIVITY_MODE from Edit scheme > Run, in the section Environment Variables if you have it set there.