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 had it on Xcode 10.1 when I accidentally pressed:

Cmd+Shift+U - ( build for Testing )

try Clean (Cmd+Shift+K) and then:

Cmd+Shift+R ( build for Running )