Eu substituo o zBar SDK no meu projeto e enfrento o problema.

ld: file is universal (3 slices) but does not contain a(n) armv7s slice: /Volumes/ZBarSDK/ZBarSDK/libzbar.a file '/Volumes/ZBarSDK/ZBarSDK/libzbar.a' for architecture armv7s
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Eu fiz o download do SDKhttp://nerdvision.net/app-development/ios/zbar-sdk

P.S. No simulador funciona.