title: What i should to do in didreceivememorywarning
body: <p>I have an app with feed like instagram. When I scroll it loads more and more images.
  So at one moment iOS sent me memory warning and I don't know what i should to do.
  If I make array(feed) is equal to nil, nothing happens</p>
  
  <p>here's my object allocations:
  <img src="https://i.stack.imgur.com/L1nFs.png" alt="enter image description here"></p>