Xcode, Duplicate symbol _main

Question

I have duplicate symbol _main.

The problem is it says \"Duplicate symbol _main in /Users/.../i386/main-B9843B6026D6EFA4.o and /Users/.../i386/main-B9843B6026D6EFA4.o

Answer 1

In my case, I declared an NSString in my constants file (imported by many classes) but forgot to define it as static!!

e.g. NSString* PARAMS = @"paramA"; should be: static NSString* PARAMS = @"paramA";

Reading the full error message allowed me to figure this out: "Duplicate symbol PARAMS". Don't be afraid and try to understand error messages! Sometimes they might even tell you exactly what you did wrong.