title: How can I cancel an asynchronous call through NSURLConnection sendAsynchronousRequest?
body: <p>I've got a web service call performing some validation on user input in real time.  I'd like to use <code>[NSURLConnection sendAsynchronousRequest]</code> on the validation (which was introduced in iOS 5), but cancel it if the user changes the input field content in the mean time.  What is the best way to cancel a current request?</p>