title: Xcode changes unmodified storyboard and XIB files
body: <p>Storyboards are rather a royal pain from a git workflow perspective when multiple people are collaborating on them. For example, the XML in the .storyboard file has its starting <code>&lt;document&gt;</code> tag's <code>toolsVersion</code> and <code>systemVersion</code> attributes altered by whatever configuration the most recent file manipulator happens to be running. Synchronizing everybody's Xcode versions precisely seems to help with <code>toolsVersion</code>, but <code>systemVersion</code> changes no matter what, depending on the specific Mac and/or OS X version the developer is running.</p>
  
  <p>This is idiotic, but mostly harmless. What worries us, though, is that at other times some other changes are automatically made to the storyboard just by opening them after a <code>git pull</code>. That is to say, Alice makes changes to a storyboard, commits and pushes them to the repository. Bob then pulls Alice's changes and opens up the storyboard to make further changes. The moment he opens the storyboard, the file icon immediately changes to a modified-but-unsaved state, and a <code>git status</code> shows that any number of weird changes have occurred. All this without Bob having changed anything or saved the file himself.</p>
  
  <p>The most common automated change we're seeing is the disappearance or reappearance of the entire <code>&lt;classes&gt;</code> tag hierachy near the end of a storyboard file. We haven't figured out what is causing this. We may have several localized versions of a storyboard in various .lproj directories, and when opening them inside Interface Builder, the class hierarchy may spontaneously be removed from some and added into others, or left alone in some. This causes a lot of noise in <code>git diff</code>, but it doesn't actually break any functionality. We will often selectively add the actual changes we made into git's index, commit those, and then just discard the spontaneous, nonsensical <code>&lt;classes&gt;</code> changes. This is to keep commits small and nice, as they should be. Eventually, though, it just becomes too much to bother with since Xcode keeps re-doing the changes, and someone just ragecommits them along with some other stuff... which is fine until someone else's Xcode decides to want to change them back for no apparent reason. (Our commit history has a lot of swearing over this.)</p>
  
  <p>Is anyone else seeing this behaviour? Is this an Xcode bug or a configuration issue on one or more of our developer Macs? We've seen some similar behaviour when collaborating with XIB files, but storyboards seem more susceptible to this.</p>