title: Detect if UIDatePicker is rolling?
body: <p>I'm using a UIDatePicker in a modal view, to select a date. I found that if the view is closed while the date picker is still rolling, I got a EXC_BAD_ACCESS.</p>
  
  <p>How can I detect of the date picker is rolling when the user tab a button?</p>
  
  <p>I had two ideas:</p>
  
  <p>1) detect if the value has changed with this:</p>
  
  <pre><code>[myDatePicker addTarget:self action:@selector(valueChanged:) forControlEvents:UIControlEventValueChanged];
  </code></pre>
  
  <p>But I would need to be able to detect if the value WILL change.</p>
  
  <p>2) check if the date is valid, but when the date picker is rolling, the previous date is returned, and of course is valid.</p>
  
  <p>Any ideas?</p>