How to reset warnings in Xcode 4

Is there a way to reset all warnings/errors in a Xcode 4 project? Xcode 4 shows me errors and warnings e.g. Unused variable 'pageType' which is has been removed weeks ago or 'XXXXViewController' undeclared (first use in this function) which was only for testing p开发者_JAVA百科urposes and has also gone.

I can't find any options how to get rid of these messages! Andy tips? Thank you!

Probably time to remove the project's derived data. Open the organizer, then the Projects tab. Select your project then hit the delete button next to the derived data path (to the right). Confirm and let it re-index your project.