title: Find when picker view selection changes?
body: <p>Is there any way I can have an object receive a message when the user changes the selected row in the picker view? My pickerview has two components and it is dismissed when the user taps the screen once. But I need to gray out certain options in the second component depending on which option in the first component is chosen.</p>
  
  <p>One other option is to use a timed function to periodically check which row is selected, but that's really hacky. Are there any delegate functions I can use?</p>