Is there a way to tell which version of Unity an Xcode Project was built with?

In the past 6 months I've had to manually revert my Unity copy to append a previously-created XCode project no less than 3 times. This is fairly common for projects with Native Code or iOS SDK implementations, when you come on as a contractor since you don't want to have to and add back in all the native code.

Unity does not let you append an iOS project unless you are on the exact version of Unity that the project was built on. (With good reason!)

However, I have yet to find anyway of determining what version of Unity an XCode project has been built on based on the XCode project alone. I don't think it's in the Info.plist or the AppController. This is made more annoying by the fact that Unity needs to reimport the assets each time you change versions.

Has anyone figured out a way to determine the Unity version an Unity XCode project has been built with?