title: Xcode - How to fix 'NSUnknownKeyException', reason: … this class is not key value coding-compliant for the key X" error?
body: <p>I'm trying to link a <code>UILabel</code> with an <code>IBOutlet</code> created in my class.</p>
  
  <p>My application is crashing with the following error. </p>
  
  <p>What does this mean? </p>
  
  <p>How can I fix it?</p>
  
  <blockquote>
    <p>*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[&lt;UIViewController 0x6e36ae0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key XXX.'</p>
  </blockquote>