It’s not uncommon for a server to require credentials for access. A common example is a password protected directory on a web-server that will prompt for a username and password before allowing access.
When using a NSURLRequest object to access a server, the delegate methods of NSURLConnection offer a means to be notified when an authentication challenge has been requested.
This post will show one approach for managing URL requests that require authentication.
Initiate the URL Request
/*--------------------------------------------------------------------------- * Begin the authentication process *--------------------------------------------------------------------------*/ - (void)startAuthentication { NSURL *url = [NSURL URLWithString:@"http://protectedURL.com"]; NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url]; // Start the connection request // Assumes NSURLConnection *urlConnection is defined as an // instance variable urlConnection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self]; }
Answer Authentication Challenge
If an authentication challenge is returned from the URL request, the method below will be called. To respond to the challange, create a NSURLCredential object, setting the username and password.
Notice that we can check to see how many times the challenge/response has failed and present an error message as needed.
/*--------------------------------------------------------------------------- * Received a server challenge *--------------------------------------------------------------------------*/ - (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge { // Access has failed two times... if ([challenge previousFailureCount] > 1) { [urlConnection release]; UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Authentication Error" message:"Too many unsuccessul login attempts." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; [alert show]; [alert release]; } else { // Answer the challenge NSURLCredential *cred = [[[NSURLCredential alloc] initWithUser:@"admin" password:@"password" persistence:NSURLCredentialPersistenceForSession] autorelease]; [[challenge sender] useCredential:cred forAuthenticationChallenge:challenge]; } } /*--------------------------------------------------------------------------- * Finished loading URL *--------------------------------------------------------------------------*/ - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"Connection success."); [urlConnection release]; } /*--------------------------------------------------------------------------- * URL connection fail *--------------------------------------------------------------------------*/ - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"Connection failure."); [urlConnection release]; }
