Basic auth iOS 6 - Not working - ios

Question

I am trying create a login screen which sends login info sharepoint server and i expect to be able to successfully login.
There are plenty of old examples and libraries which I am not able to use. But after spending hours I found this link to have the crux of all
http://transoceanic.blogspot.com/2011/10/objective-c-basic-http-authorization.html
My code looks like this now:
- (void) startLogin {
NSURL *url = [NSURL URLWithString:#"http://site-url.com"];
NSString *loginString =(NSMutableString*)[NSString stringWithFormat:#"%#:%#",usernameTextField.text,passwordTextField.text];
NSData *encodedLoginData=[loginString dataUsingEncoding:NSASCIIStringEncoding];
NSString *authHeader=[NSString stringWithFormat:#"Basic %#", [encodedLoginData base64Encoding]];
NSURLRequest *request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:3.0];
// [request setValue:authHeader forKey:#"Authorization"];
[request setValue:authHeader forHTTPHeaderField:#"Authorization"];
[request setHTTPMethod:#"POST"];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
There are three issues:
the commented out line-code doesn't give any error but it crashes on that line(while debugging)
on [request setValue:authHeader forHTTPHeaderField:#"Authorization"]; i am getting error "No visible interface for NSURLRequest declares selector setHTTPHeaderField"
Also, I am getting warning - unused variable "connection" in last line. I am not sure how this whole thing works and any simple example or correction is appreciated.
I would also like to know if there are any other simple methods for basic auth.
UPDATE: Delegate methods
- (void)connection:(NSURLConnection *)connection
didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
// Access has failed two times...
if ([challenge previousFailureCount] > 1)
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Authentication Error"
message:#"Too many unsuccessul login attempts."
delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
}
else
{
// Answer the challenge
NSURLCredential *cred = [[NSURLCredential alloc] initWithUser:#"admin" password:#"password"
persistence:NSURLCredentialPersistenceForSession];
[[challenge sender] useCredential:cred forAuthenticationChallenge:challenge];
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSLog(#"Connection success.");
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(#"Connection failure.");
}

Answer 1

Change NSURLRequest to NSMutableURLRequest to access it's setValue:forHTTPHeaderField method, and add a HOST header as well if it's a shared web host.
At the end, you have to start the connection:
[connection start];
Also, make sure you've set up your NSURLConnectionDelegate delegate methods for the call backs.