title: iOS UITableViewCell Images from URL
body: <p>I am loading images in my <code>UITableViewCell</code> from some web url and those images are in size around 80-100 kb per image. Everything works fine when i download images asynchronously <code>but when i scroll the tableview, images start again downloading. Can i get rid of this</code> as i have only limited no of rows. 
  I want if images from url download once should not be download again as it does  makes view not comfortable for users when images starts downloading again.</p>
  
  <p>I am using below code to load images in <code>CellforRowAtIndexPath</code>:</p>
  
  <pre><code>dispatch_async(dispatch_get_global_queue(0,0), ^{
      NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString:url];
      if ( data == nil )
          return;
      dispatch_async(dispatch_get_main_queue(), ^{
          cell.eventImage.image=  [UIImage imageWithData:data];
  
      });
  });
  </code></pre>