title: Issue with code autocompletion / syntax highlighting in Xcode 4.x
body: <p>I am having a rather strange issue in Xcode on one of my projects.</p>
  
  <p>When I start to write my code, I am used to the auto-completion suggesting numerous entries for me. For some reason, since yesterday, this has stopped working. I now get strange auto-completion entries such as "and", "the", "Andy", "MyCompanyName" etc.</p>
  
  <p>This never happened before and so I am confused as to why it has occurred now, and only on one of my projects. I searched this site for quite some time for any fixes and I've attempted to clean Derived Data, quit Xcode, delete the workspace and user files from the Xcode project and restart, but after doing so, the auto-complete works for a while, then breaks again after about 30 seconds of coding.</p>
  
  <p>I can sometimes see auto-complete solutions, but just plain text (no class indicators), then other times it stops working entirely.</p>
  
  <p>Has anybody else experienced anything like this and could provide some solution?</p>