title: How do I save memory when loading images from a URL in a Collection View?
body: <p>I have a collection view in my app and want to load images from a url. The collection view is scrollable. If the user scrolls down more images should be paginated from the url. </p>
  
  <p>What should I do with the images that I have loaded so far? One way would be to set the pointer to nil in order to free the space in the heap. But then I have to load then again, when the user scrolls up.</p>
  
  <p>Is there a better way to handle the scrolling and keep the heap memory as low as possible?</p>