title: Cache UIImage using uitableview from url
body: <p>I hava a uitableview , with custom cell containing two UImages. The logo images are taken from an online website, that's why there's a need to cache the images. Loading the image till now is made like this : </p>
  
  <pre><code> NSURL * imageURL = [NSURL URLWithString:[arra1 objectAtIndex:indexPath.row / 2]];
   NSData * imageData = [NSData dataWithContentsOfURL:imageURL];
  
   NSURL * imageURL2 = [NSURL URLWithString:[arra2 objectAtIndex:indexPath.row / 2]];
   NSData * imageData2 = [NSData dataWithContentsOfURL:imageURL2];
  
   cell.ima1.image = [UIImage imageWithData:imageData];
   cell.ima2.image2 = [UIImage imageWithData:imageData2];
  </code></pre>
  
  <p>What i learned from searching , is that dataWithContentsOfURL is not asynchronous , and while scrolling it will take a lot of time. I tried several methods but i can't seem to get to right one. This is my first time caching UIImages , i would highly appreciate a detailed explanation with implementation so i could learn aside from getting the job done.
  Many Thanks</p>