Constructs a basic authentication header from the user name and password specified, and adds it to the request headers.
It is used when the variable shouldPresentCredentialsBeforeChallenge is set to YES. Usage ODPRequest *request=[ODPRequest requestWithURL:[NSURL URLWithString:endpointUrl]]; [request addBasicAuthenticationHeaderWithUsername:"smpuser" andPassword:@"s3puser"]; [request startSynchronous];