title: Xcode 4.2 Compilation Failed with prototype cell
body: <p>I'm trying out the new Xcode 4.2 Beta and I'm wondering if my code is wrong or if I'm bumping in to an bug. </p>
  
  <p>The new Storyboard feature is promising but extremely buggy at the moment. Right now I've created an simple project with a tableview. This tableview will be "Grouped style" containing UITextFields. The new "Prototype Cell" feature of storyboard let's you create a prototype cell in GUI that you can draw with the "Reuse identifier" in the method cellForRowAtIndexPath.
  When I drag in a UITextField in this "prototype cell" and draw it out, it works great!</p>
  
  <p>However! When I reference this textfield to an outlet in my code I get the error:
  Uncategorized
  Compilation failed. Unable to write to path:...(Path to DerivedData)</p>
  
  <p>Why is this?
  Is it a bug?
  Anyone else get this? </p>