title: Image download - NSURLSession received Authentication Challenge
body: <p>I'm trying to download simple image from url 
  <a href="http://d1vqbpto5tbbz0.cloudfront.net/blog/wp-content/uploads/2014/08/25215844/ios-logo1.png" rel="nofollow noreferrer">http://d1vqbpto5tbbz0.cloudfront.net/blog/wp-content/uploads/2014/08/25215844/ios-logo1.png</a></p>
  
  <p>This is simple url access through browser without any login.</p>
  
  <p>I have tried with this code:</p>
  
  <pre><code>NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
  configuration.timeoutIntervalForRequest = timeout;
  NSURLSession *urlSession = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
  [[urlSession dataTaskWithURL:urlImage] resume];
  </code></pre>
  
  <p>For this only I am receiving authentication challenge.</p>
  
  <p>What is the reason for it?</p>
  
  <p>I have gone through stackoverflow and found these links:</p>
  
  <ul>
  <li><p><a href="https://stackoverflow.com/questions/20711816/simple-example-of-nsurlsession-with-authentication">Simple example of NSURLSession with authentication</a></p></li>
  <li><p><a href="https://stackoverflow.com/questions/21105322/ios-cocoa-nsurlsession-handling-basic-https-authorization">iOS/Cocoa - NSURLSession - Handling Basic HTTPS Authorization</a></p></li>
  <li><p><a href="https://stackoverflow.com/questions/39314034/nsurlsession-with-basic-authentication-challenge">NSURLSession With Basic Authentication Challenge</a></p></li>
  </ul>
  
  <p>In all links, there is mentioned to enter user:password. What user name and  password, I can enter?</p>