I had one problem during building application in the recent Xcode 5.1. Compilation fails with "Undefined symbols for architecture x86_64" error.
I build my project with Valid Architecture: armv7, armv7s and arm64. After switch to the newest environment (Xcode) I rebuild libzbar.a library in the same architecture ( I have done it based on solution found at: Linker Error in Xcode-5)
Maybe somebody also had same problem and finally he had solved it, please share with solution:)
I had the same problem and I solved that way:
Let me know if it works for you.