title: Fading out any content which approaches edges of UIScollView
body: <p>As the title says, I am trying to give to some UIImageViews a fading out effect as they get closer and closer to any of the four edges of my UIScrollView. Since the user can drag the UIImages, if he drags them towards the edges, they start fading out, instead of giving that cut out effect as if there were borders to the UIScrollView. I tried this tutorial:</p>
  
  <p><a href="http://www.cocoanetics.com/2011/08/adding-fading-gradients-to-uitableview/" rel="noreferrer">http://www.cocoanetics.com/2011/08/adding-fading-gradients-to-uitableview/</a></p>
  
  <p>suggested in another stack overflow question, but it can only be applied to UITableViews. I would like the image to start fading as it gets one centimeter away from the border.</p>