Xcode : Apple Mach-O linker Error

Xcode : Apple Mach-O linker Error

I made the app in Xcode 4.6 and tested in device. The app is made for both
iPhone and iPad. When I try to archive it to make .ipa file, I get this
error :
ld: file is universal (3 slices) but does not contain a(n) armv7s slice:
/Users/admin/Desktop/appName/appName/libzbar.a for architecture armv7s
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
How to set the architecture for this in Build Settings? Or is there some
different issue?