title: Why can I not switch branches?
body: <p>I'm trying to switch branches in git but I'm getting this error message:</p>
  
  <pre><code>error: you need to resolve your current index first
  </code></pre>
  
  <p>I'm using git under xcode4 </p>
  
  <pre><code>git status
  # On branch DateCode
  # Unmerged paths:
  #   (use "git reset HEAD &lt;file&gt;..." to unstage)
  #   (use "git add/rm &lt;file&gt;..." as appropriate to mark resolution)
  #
  #   both modified:      Whereami.xcodeproj/project.xcworkspace/xcuserdatauser.xcuserdatad/UserInterfaceState.xcuserstate
  #
  no changes added to commit (use "git add" and/or "git commit -a")
  Frappuccinos-MacBook-Pro:whereami
  </code></pre>