XCode: Undefined symbols for architecture arm64 error

Question

In my XCode 5 project I use RestKit for REST communication. Everything works fine with the simulators, but generating the ipa file, I get the following error:

Answer 1

It just means you are building your project also for 64bit (iPhone 5s) and nothing to worry about, see this link for some more explanations: Xcode 5 and iOS 7: Architecture and Valid architectures