title: Suggest # tags while typing (like Twitter) for iPhone UITextView
body: <p>I'd building an app that uses hashtags, like Twitter or Tweetbot. When you're typing a message, if you type the hashtag symbol, I'd like to suggest tags that match the current one you're typing.</p>
  
  <p>I've already figured out how to get the UITableView to appear and show a list of hashtags, but what I can't figure out is how to do the following:</p>
  
  <ol>
  <li>Get the <code>NSRange</code> of the current word being typed,</li>
  <li>See if that range is formatted like a hashtag (<code>NSRegularExpression @"#\\w\\w*"</code>)</li>
  <li>(From here on out, I've got the code figured out to search for matching hashtags and show them in the UITableView)</li>
  </ol>
  
  <p>Can anyone help me with steps 1 and 2? I've been thinking about using <code>textViewDidChange:</code>, but I'm concerned that the app's performance might suffer if I'm constantly running methods every time the characters change.</p>
  
  <p>Thanks!</p>