title: What is the purpose of Compile Sources in Xcode?
body: <ul>
  <li>What is the purpose of Compile Sources in Xcode? </li>
  <li>Does every file in your project need to in there? </li>
  <li>If I add files to a project, does
  every file get added to compile sources.</li>
  </ul>
  
  <p><img src="https://i.stack.imgur.com/QgRMB.png" alt="enter image description here"></p>