title: Convert a NSString to unicode
body: <p>I have some non-european characters like @"á".</p>
  
  <p>And I'm looking for a method that can convert those character to unicode like this online tool</p>
  
  <p><a href="http://ratfactor.com/utf-8-to-unicode" rel="nofollow">UTF-8 to Unicode Converter</a></p>
  
  <p>Example: á = \u00E1</p>
  
  <p>And I can get "\u00E1" like a NSString.</p>
  
  <p>Anyone can show me how? </p>