Since XCode 9, I've been seeing build errors hang around after they're fixed. It's very annoying because they obscure actual build errors.
For example, a cocoapod was not in the right place, so the import statement was flagged. I fixed the dependency, ran the app, it ran fine, but the build error persisted for several more runs until I ran in a different simulator.
Cleaning the build folder (even with OPTION key)did not help.
Is there some other way to clear build errors?
Same-only-different from an option-clean build folder is to do a 'delete derived data' on that build folder. Using Xcode prefs/locations will show that main location in the finder - you'll need to id the last build and **** it out from there.
'option-clean' wipes the folder itself, 'clean' wipes data for the target only, but has never made any difference for me...note that with the new build system, option-clean is now the default and clean is, thankfully, gone.
In some cases, it can help to delete all versions of the app you're working on from the simulator/device, before going again...after a jolt from an option-clean, of course.
If you think indexing is contributing to the issue, supposedly you can disable it via terminal (1 is disable, 0 is enable):
defaults write com.apple.dt.XCode IDEIndexDisable 1- may require you to restart Xcode for it to take. Disabling will take away search and autocomplete, tho, so...
Pretty often I had to clean the build folder, quit XCode and reopen. Usually, that "flushed the caches" and solved the problem.
Looks like CBF in Xcode 9.2 had a bug. Just found this in the Xcode v9.3 beta release notes:
“Fixed an issue in which the Clean Build Folder command could fail to complete."
4 years later, it only gets worse...
Still happening with Xcode 14.3. Very annoying.
This is a classic XCode bug, still happening with XCode 15.1.
The only way I have found to fix it is to delete derived data