title: iOS - i receive memory warnings but have no idea why
body: <p>I am developing for the iOS and checking my app with IPhone and IPad.</p>
  
  <p>I receive many memory warnings (didReceiveMemoryWarning is called) but have no idea why.
  My app is using ~35MB in the peak points, and 4-5 MB when it the lowest point.</p>
  
  <p>I tried to find leaks using 'instruments' but could not find any critical issues.</p>
  
  <p>Is there a good way to find out why the system sends memory warnings?</p>