Linker command failed with exit code 1 (duplicate symbol)

Question

I developing a game in Unity and I have used Admob, Facebook and GameCenter in it. It was working fine on iOS until I have added the OpenIAB for in-app purchase, though it works

Answer 1

I have recently face the same issue. I know Umer Azeem got the answer but to help someone else who may suffer from the same issue I was in.
According to my application flow I am using printer related third party class to print. To use that I have created object of that class in both of my files ImagePrintViewController and PrintResultViewController separately and passed required data to it.

In my scenario I am getting same error with variable name like _printerSetup in two of my files/Library/Developer/Xcode/DerivedData/../x86_64/ImagePrintViewController.o and /Library/Developer/Xcode/DerivedData/../x86_64/PrintResultViewController.o.
I have search in both of my file for the above variable name. But I couldn't find that.

After searching long on this I got a idea to delete reference of my second file i.e. BRPrintResultViewController.h and BRPrintResultViewController.m after merging code in my first file.

With this I found my solution and my code runs fine after this.

Answer 2

Look up in your project for:

MakeStringCopy

And make sure it exists (if exists) only once. If it appears more then once, rename one (make sure to rename it where it being called as well) and try to build again.