Xcode shows many errors but program compiles and runs fine (in both simulator and device)

Question

After installing the CocoaLumberjack\' log compressor class I\'ve been getting this annoying behavior: Xcode complains that there are many undeclared identifiers and gives m

Answer 1

I was having issues with a library installed via cocoapods. Going to Build Settings and searching for 'Allow Non-modular Includes In Framework Modules' then setting it to Yes did the trick.

Answer 2

Open build settings and set "Precompile Prefix Header" to "No", that solved my problem.

Kudos for: https://stackoverflow.com/a/7035492/936957

Answer 3

Not bad, If you follow these Steps-

1-Clean Xcode(Cmd+Shif+K).

2- Clear Derived Data(Cmd+Shift+G).

Enter this path( ~/Library/Developer/Xcode/DerivedData/).

3- Quit and open again Xcode.

Answer 4

After update to Xcode 11, I met the same problem. I tried all the mentioned advices (cleaning folders, turning on/off different settings, restarting xCode), but nothing helped. Also, I have a big project in C, so, I'd like to keep using precompiled headers.

Finally I found that simple restart of Mac OS solves the problem! It's really weird behaviour, but I'm happy anyway that I found a solution – it's hard to code when lots of colourful error messages float around.