title: NSString emoji literal
body: <p>I'm trying to get the <code>NSString</code> for the smiling <code>emoji</code> whose utf-8 code is: <code>0xF0 0x9F 0x98 0x84</code>.
  This works:</p>
  
  <pre><code>NSString *smile = [NSString stringWithUTF8String:"\xf0\x9f\x98\x84"];
  </code></pre>
  
  <p>but this doesn't:</p>
  
  <pre><code>NSString *smile = @"\uf0\u9f\u98\u84";
  </code></pre>
  
  <p>I get the error message: "<code>Incomplete universal character name</code>". Can anyone help me with this? Thanks.</p>