title: willSendRequestForAuthenticationChallenge purpose
body: <p>I was looking at Box Oauth2.0 View Controller:
  <a href="https://github.com/box/box-ios-sdk-v2/blob/master/BoxSDK/OAuth2/BoxAuthorizationViewController.m" rel="nofollow">https://github.com/box/box-ios-sdk-v2/blob/master/BoxSDK/OAuth2/BoxAuthorizationViewController.m</a></p>
  
  <p>They have the following code:</p>
  
  <pre><code>- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
  {
  </code></pre>
  
  <p>What is the purpose of including such a code?</p>
  
  <p>Is it neccesary when showing an oauth2.0 flow in webview?</p>