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

You can get this for method names too!

I got duplicate symbol _runOnMainQueueWithoutDeadlocking after adding DBCamera via CocoaPods and it was because both my category on NSObject (NSObject+Tools.h) and the GPUImage dependency file GPUImageOutput.m both had a method called 'runOnMainQueueWithoutDeadlocking'.

I was fortunate enough to be able to remove my method from code because I wasn't actually using it anymore or anywhere.

It's probably what I deserve for putting a category on NSObject.

Answer 2

If still have a problem, try to search like this: "int main(", and remove those files except main.m

Answer 3

I also had this problem and it was caused by code I imported from another project. I did a grep for "int main" in my project directory:

grep -nr "int main" .

and found

./main.m:13:int main(int argc, char *argv[])
./IMPORTED_DIR/main.m:13:int main(int argc, char *argv[])

the IMPORTED_DIR contained the extra main.m that was causing the error for me

I removed that file from the Project -> Targets -> Build phases -> Compile sources list and then it compiled

Answer 4

I was facing the same issue with using two third party framework. (AppLovin and Flurry) And I came to know that by removing "all_load" from "Other Linker Flags" in build settings.

Answer 5

Just got this problem myself, but after reading huggie's solution which did lead me on the right track, I was left a bit confused. So current solution in Xcode: Choose project, target -> build phases and click validate settings

Then Xcode will auto fix its own mistake. It is always nice when the tools tries to stop your progress ;)

Answer 6

In my case, I had imported another project, in order to utilize a library contained within. It resulted my project having two main.m files.

This was even more confusing, since the error didn't show up until several builds later.