title: How can I use .xcconfig files in Xcode 4?
body: <p>I just switched over to Xcode 4 and I'm having trouble working with .xcconfig files for build settings. My targets that already had files assigned in Xcode 3 are all set up - a column titled Config.file shows up in the Levels view of Build Settings. But I can't figure out how to edit the columns in this view or where to put an .xcconfig file to attach it to a new target. I've looked online and haven't found an answer. Anybody know how to do this?</p>