HTTP Authentication in iPhone

I am hoping someone can help me with a question i have relating to 开发者_运维技巧 Authentication in Xcode Basically i have a MS Sharepoint server which return XML. Im Having this piece of code for authentication but it is unaccessible.

NSString *urlString = @"http://example.com/";

NSMutableURLRequest *request= [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:@"POST"];

NSString *str1 = [NSString stringWithString:@"username:password"];
NSData *myDate = [str1 dataUsingEncoding:NSUTF8StringEncoding];
NSString *str2 = [Base64 encode:myDate];
NSLog(@"%@ str1 %@", str2,str1);

[request addValue:[NSString stringWithFormat:@"Basic %@",str2] forHTTPHeaderField:@"Authorization"];

NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *str = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSLog(@"%@", str);

Even I m passing correct credentials, but the server is not accepting. It returns

401 - Unauthorized: Access is denied due to invalid credentials.

Can any1 Help?

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Use NSURLConnection's -connection:didReceiveAuthenticationChallenge: delegate method to detect when authentication is required. In short, you'll be using NSURLCredential instances to attach authentication to the request.

The docs have a good overview and code sample:

Responding to an Authentication Challenge

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Consider using the open source ASIHTTPRequest class as it makes authenticated requests pretty simple.