title: Xcode 4.2 how to automatically compile source files dragged into project?
body: <p>A quick question,</p>
  
  <p>Up to date, all of my Xcode 4.2 projects automatically compiled everything that I dragged into the list of sources on the left. But recently this stopped happening. The files that I drag into the project just sit there, and I have to manually add them to the project>build phases > compile sources. </p>
  
  <p>How can I restore the Xcode's ability to automatically compile everything that I drag and copy into the project?</p>
  
  <p>Thank you!</p>