title: Changing UITextField in UITableViewCell value does not trigger KVO in iOS 7
body: <p>I have a UITableView that has cells containing text fields. As the user edits each text field, I need to keep track of the cell's text field value (even when the cell is no longer displayed, so simply tracking the text field does not work). So I used Key-Value Observing and set an observer for each text field in my UITableViewController subclass:</p>
  
  <pre><code>[cell addObserver:self forKeyPath:@"textField.text" options:NSKeyValueObservingOptionNew context:nil];
  </code></pre>
  
  <p>And save new changes to the text field in the class's <code>observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context</code> method. </p>
  
  <p>This works great in iOS 6, but in iOS 7 KVO isn't called when the user changes the text field value. Apparently the setter method called by pressing "done" on the keyboard doesn't call KVO anymore. </p>
  
  <p>Is there a workaround to this? Or a better way of listening for this change? I need to know what cell the text field belongs to, so implementing the text field's method <code>editingDidEnd</code> doesn't work for me.</p>
  
  <p>Thanks in advance.</p>