title: "Non-breaking space (U+00A0) used instead of regular space" warning in Xcode
body: <p>When typing a <kbd>space</kbd> character in Xcode, a warning appears sometimes:</p>
  <blockquote>
  <p>Non-breaking space (U+00A0) used instead of regular space</p>
  </blockquote>
  <p>Earlier Xcode versions display these messages:</p>
  <blockquote>
  <p>Treating Unicode character as whitespace</p>
  </blockquote>
  <p>or</p>
  <blockquote>
  <p>Invalid character in source file</p>
  </blockquote>
  <p>If I re-write the character, the warning disappears. What causes this?</p>