title: How is [UITextField rac_newTextChannel] used to two-way bind UITextField text to a model object in ReactiveCocoa?
body: <p>Say I have the following:</p>
  
  <pre><code>UITextField *textField = [[UITextField alloc] init];
  </code></pre>
  
  <p>and a model object:</p>
  
  <pre><code>JSModel *model = [[JSModel alloc] init];
  </code></pre>
  
  <p>The following will give me a two-way binding (perhaps there are disadvantages with this approach that I'm not seeing?):</p>
  
  <pre><code>RAC(model, text) = textField.rac_textSignal;
  RAC(textField, text) = RACObserve(model, text);
  </code></pre>
  
  <p>How can <code>[UITextField rac_newTextChannel]</code> be used to achieve this two-way binding?</p>