NSMutableURLRequest *request = [[NSMutableURLRequest alloc]
                                initWithURL:[NSURL
                                             URLWithString:@"https://testservice.fiamm.com/token"]];

[request setHTTPMethod:@"POST"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-type"];

NSString *postString = @"username=TestIphone&Password=T3st1ph$n&Grant_type=password";

[request setValue:[NSString stringWithFormat:@"%d", [postString length]] forHTTPHeaderField:@"Content-length"];

[request setHTTPBody:[postString
                      dataUsingEncoding:NSUTF8StringEncoding]];

// Fetch the JSON response
NSData *urlData;
NSURLResponse *response;
NSError *error;

// Make synchronous request
urlData = [NSURLConnection sendSynchronousRequest:request
                                returningResponse:&response
                                            error:&error];

// Construct a String around the Data from the response
NSString *strFiamm = [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding];

http://testservice.fiamm.com/token
username=TestIphone
Password=T3st1ph$n
Grant_type=password

403 - Forbidden: Access is denied.
You do not have permission to view this directory or page using the credentials that you supplied.

-(void) connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *) challenge {

    if ([challenge.protectionSpace.authenticationMethod isEqualToString: NSURLAuthenticationMethodServerTrust])
    {

        NSURL* baseURL = [NSURL URLWithString:@"yourURL”];

        if ([challenge.protectionSpace.host isEqualToString:baseURL.host])
        {
            SecTrustRef trust = challenge.protectionSpace.serverTrust;

            NSURLCredential *cred = [NSURLCredential credentialForTrust:trust];

            [challenge.sender useCredential:cred forAuthenticationChallenge:challenge];

        }
        else
        NSLog(@"Not trusting connection to host %@", challenge.protectionSpace.host);

    }
    [challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
}