Xcode 5: How to revert to an old version of a XIB

I have 'legacy code'.  It has been a few years since an app I wrote first debuted on the App Store, but it all still works.  With iOS 7, I decided to sprinkle in some AutoLayout to bring some parts of the app into the modern era, but ran into some problems and decided after a few commits that I wanted to back out.  I decided to roll the XIB back to it's original pre-iOS 7 self.  Except when I tried to open it, I got this really odd error: 

The document could not be opened. Could not determine the type of data.

At this point Xcode can't determine what kind of document it is, for some reason, and just gives up. I scoured the Internet for a half-hour before it donned on me: Xcode 5 makes updates old XIBs to a new XML structure when they are opened to make them more stream-lined and easier to diff, like storyboards. In order to rollback to the old version it takes a few steps:

  1. DO NOT revert your code first.
  2. Go into the document inspector in Interface Builder and change the "Opens in" attribute to "Xcode 4.6"
  3. Accept the warning that you'll lose iOS 7 capability.
  4. Roll back the changes in git.
  5. Change the "Opens in" attribute back to "Default (5.0)".
  6. Presto-chango: you have now rolled back to the old revision of your XIB and it's now in the new Xcode 5 format.
  7. Commit and push (you don't want to have to do this again, do you?)

I suspect what is happening is that Xcode attempted to parse the old format, thinking it was in the new format, and then gets discombobulated.  Interesting bug and a use case that does not appear to be in a unit test. :)

Posted on Jan 10
Written by Wayne Hartman