Xcode 10+: how to switch to legacy build system?

Question

There seem to be some problems with the new build system in Xcode 10. How do I switch to the old (legacy) build system?

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NOTE: While one can apparently still use it for a bit longer (in June 2022), the legacy build system is marked deprecated in Xcode 13.4.1)

Answer 1

You can switch back to the previous (legacy) build system from the menu by File > Workspace Settings... (or Project Settings...):

This brings up a dialog where you can change the Build System to Legacy Build System:

Hat tip to this answer. There's also a video here.