You can compute the necessary Authorization header yourself and manually apply it to the outgoing NSURLRequest before creating the NSURLConnection, as in:
NSMutableURLRequest *someURLReq = ...
NSString *auth = ...
[someURLReq setValue:auth forHTTPHeaderField:@"Authorization"];
The content of the auth
in the case of HTTP basic authentication, using Dave Dribin's base64 NSData category would be:
NSString *username = ...
NSString *password = ...
NSString *combo = [NSString stringWithFormat:@"%@:%@", username, password];
NSData *comboData = [NSData dataWithBytes:[combo UTF8String] length:combo.length];
NSString *auth = [NSString stringWithFormat:@"Basic %@", [comboData encodeBase64]];
Note that this is not encryption, the password is plain text for all practical purposes, and will be sniffed unless you're on an SSL connection.