title: How to tell if a UITextField is firstResponder
body: <p>I'm working on an app that has a signup feature.  The signup process is broken up into 3 different views, each of which has 2 UITextField to take user input.  I have also implemented the <code>UITextFieldDelegate</code> methods;</p>
  
  <pre><code>- (void)textFieldDidBeginEditing:(UITextField *)textField;
  - (BOOL)textFieldShouldEndEditing:(UITextField *)textField;
  - (void)textFieldDidEndEditing:(UITextField *)textField;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>- (BOOL)textFieldShouldReturn:(UITextField *)textField;
  </code></pre>
  
  <p>Depending on which <code>UITextField</code> is in focus will determine what method is called when the user taps the return key on the keyboard.  I would like to just call my <code>resignFirstResponder</code> method for the first 4 <code>UITextField</code>s but on the last textField I would like to call my join method when return is pressed.</p>
  
  <p>So my question is; How can I determine which <code>UITextField</code> just called the <code>textFieldShouldReturn:</code> method?</p>
  
  <p>As always, thanks in advance!</p>