When using a NSURLConnection with a synchronous connection using sendSynchronousRequest and Basic Authentication, the following error may be seen:

"The operation couldn’t be completed. (NSURLErrorDomain error -1012.)"

This evaluates to the constant:

NSURLErrorUserCancelledAuthentication
Returned when an asynchronous request for authentication is cancelled by the user.

Use the NSURLCredentialStorage, and ensure the authenticationMethod is set to NSURLAuthenticationMethodHTTPBasic, persistence is set to NSURLCredentialPersistenceForSession or NSURLCredentialPersistencePermanent, and all parameters are correct, including host, username, password and in particular, realm:

NNSURLCredential *credential = [[NSURLCredential alloc]
                                initWithUser: @"username"
                                password: @"password"
                                persistence: NSURLCredentialPersistenceForSession];                              
NSURLProtectionSpace *protectionSpace = [[NSURLProtectionSpace alloc]
                                         initWithHost: @"server.domain.com"
                                         port: 80
                                         protocol: @"http"
                                         realm: @"Secure Area"
                                         authenticationMethod: NSURLAuthenticationMethodHTTPBasic];
[[NSURLCredentialStorage sharedCredentialStorage] setDefaultCredential:credential forProtectionSpace:protectionSpace];

URL Loading System Programming Guide
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html

[NSURLCredentialStorage sharedCredentialStorage]
http://developer.apple.com/library/ios/#documentation/MediaPlayer/Reference/MPMoviePlayerController_Class/MPMoviePlayerController/MPMoviePlayerController.html

Foundation Constants Reference
http://developer.apple.com/library/mac/#documentation/cocoa/Reference/Foundation/Miscellaneous/Foundation_Constants/Reference/reference.html