title: programmatically highlight UIBarButtonItem
body: <p>after tapping the 'record' BarButtonItem I would like to keep it programmatically highlighted until the recording is over. The highlighting graphics of iOS are very good, therefor I would like to remain or set that state.</p>
  
  <p>Up to now I found 'setSelected' and 'setHighlighted' but these do not work on a UIBarButtonItem.
  Any suggestions on how to solve this? Thank you in advance, Koen.</p>