NSURLSessionConfiguration HTTPAdditionalHeaders not set

Question

Authorization header is set in NSURLSessionConfiguration, however it is not attached to NSURLSessionDataTask. Is this a bug in Foundation framework?

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
[configuration setHTTPAdditionalHeaders:@{@"Authorization":@"123"}];

// Initialize session with NSURLSessionConfiguration
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
NSURLSessionDataTask *sessionTask = [session dataTaskWithRequest:request
                                        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
}];

[sessionTask resume];

Answer 1

In the NSURLSessionConfiguration document,

An NSURLSession object is designed to handle various aspects of the HTTP protocol for you. As a result, you should not modify the following headers:

Authorization

Connection

Host

WWW-Authenticate