title: iOS UISlider not moving when I swipe, even though other UI elements are fine
body: <p>I've created a simple xib file with three buttons and a UISlider.</p>
  
  <p>When I start the app on my phone I'm able to tap the buttons no problem, but the UISlider is locked and doesn't move..</p>
  
  <p>However if I keep trying to move it with my finger it eventually scrolls left and right fine, but only after about a minute of furious screen swiping..</p>
  
  <p>I thought it might be because it was hidden behind something onscreen (not that there's anything for it to hide behind) so I did 'arrange -> send to front', but this doesn't help.</p>
  
  <p>Does anyone know why it might be doing this?</p>