title: Xcode: project navigator, difference between Yellow folder and blue folder
body: <p>I want to know the difference between a blue folder and a yellow folder in Xcode.</p>
  
  <p><img src="https://i.stack.imgur.com/GUe0V.png" alt="enter image description here"></p>
  
  <p>I found <a href="https://stackoverflow.com/questions/8487760/what-is-a-blue-folder-in-xcode">this</a> but doesn't clarify my doubts!</p>