title: Using watch crown to control a WKInterfaceSlider
body: <p>I would like to use the apple watch crown to control a slider. Is this possible?</p>
  
  <p>If so, how?</p>
  
  <p>Apple uses it to change the colours on the UI of the watch.</p>
  
  <p><strong>EDIT:</strong> so it seems not possible at the moment (see answers below). Is important to notice that in two weeks time (Apple WWDC 2015) this could change (maybe a Watch OS for independent apps?)</p>