title: Detect Unicode characters in NSString on iPhone
body: <p>I am working on an SMS application for the iPhone. I need to detect if the user has entered any unicode characters inside the NSString they wish to send. </p>
  
  <p>I need to do this is because unicode characters take up more space in the message, and also because I need to convert them into their hexadecimal equivalents.</p>
  
  <p>So my question is how do I detect the presence of a unicode character in an NSString (which I read from a UITextView). Also, how do I then convert those characters into their UCS‐2 hexadecimal equivalents?</p>
  
  <p>E.g 繁 = 7E41, 体 = 4F53, 中 = 4E2D, 文 = 6587</p>