duplicate symbols for architecture armv7
This can happen if you accidentally #import a .m file instead of the .h!
Generally, this kind of error occurs due to duplicate classes and xibs in your project folder. For example, in my project I had some class files duplicated(.h/.m files). You can see these duplicate classes under target->Build phases->compile sources.
Just look and remove extra classes. Problem will be solved.
Happens with static variables in a header file (header file included in more than one implementations file).