title: What is the biggest difference between NSURLConnection and NSURLSession
body: <p><a href="https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/URLLoadingSystem/Articles/UsingNSURLSession.html#//apple_ref/doc/uid/TP40013509-SW1">NSURLSession</a> is new network SDK than <a href="https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html#//apple_ref/doc/uid/20001836-BAJEAIEE">NSURLConnection</a> from Apple. 3rd old choice is CFNetwork.</p>
  
  <p>Question here is to figure out the biggest difference between them to understand why Apple is evolving like these. </p>
  
  <p>Thanks</p>