title: Why does Xcode auto-completion not work and keep showing errors?
body: <p>I am new to Xcode. After a few days of "normal" use, where I didn't get any problems of any kind, Xcode stopped working properly.</p>
  
  <p>The auto code completion now gives me only the methods ("M"). If, for example, I'm in "ViewController.swift" and write <code>if ...</code>, an error appears and does not show me the hint. It seems as if it doesn't "import" the right libraries.</p>
  
  <p><a href="http://cl.ly/image/1u3J120y3A1J/Image%202015-01-22%20at%207.32.57%20PM.png" rel="nofollow noreferrer">img1 http://cl.ly/image/1u3J120y3A1J/Image%202015-01-22%20at%207.32.57%20PM.png</a></p>
  
  <p><a href="http://cl.ly/image/0r1a1x210U17/Image%202015-01-22%20at%207.33.13%20PM.png" rel="nofollow noreferrer">img2 http://cl.ly/image/0r1a1x210U17/Image%202015-01-22%20at%207.33.13%20PM.png</a></p>
  
  <p><img src="https://i.stack.imgur.com/ofY5E.png" alt="img3"></p>