Replacing NSTimer
<p>using iphone sdk 4. I have an NSTimer that calls a method every 3 seconds, however the emethod being called is causing the UI to go unresponsive. I thought the NSTImer callback would happen in a separate thread to the main thread but it appears this is not so. </p>

<p>How can i replace this with an NSOperation or something so the method is still called every 3 seconds but in a background thread</p>
