How to add Headers to Request in AfNetworking 3.0?

Question

I am confused with adding headers in 'AFNetworking 3.0'. In the previous version, there is function known as RequestSerializer. How can I add specific headers to a Mutable Request?

{ 
NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:@"http://example.com/" parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {

 NSString *path = [[NSBundle mainBundle] pathForResource:@"uploadedImage_3" ofType:@"jpg"];
[formData appendPartWithFileURL:[NSURL fileURLWithPath:path] name:@"file" fileName:@"filename.jpg" mimeType:@"image/jpeg" error:nil];
} 
error:nil];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[request addValue:@"8b10056e-59e6-4d2b-aa4f-b08f8afff80a" forHTTPHeaderField:@"session_key"];
[request addValue:@"0" forHTTPHeaderField:@"resume_key"];

AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

NSURLSessionUploadTask *uploadTask;
uploadTask = [manager
            uploadTaskWithStreamedRequest:request
            progress:^(NSProgress * _Nonnull uploadProgress) {
              // This is not called back on the main queue.
              // You are responsible for dispatching to the main queue for UI updates
              dispatch_async(dispatch_get_main_queue(), ^{
                //Update the progress view
                [_progressView setProgress:uploadProgress.fractionCompleted];
              });
            }
            completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
              if (error) {
                NSLog(@"Error: %@", error);
              } else {
                NSLog(@"%@ %@", response, responseObject);
              }
            }];

[uploadTask resume];
}

Is this is how I should add the headers to the MutableURLRequest?

NSLocalizedDescription = Request failed: unsupported media type (415)}

I am currently getting an error like above.

Answer 1

Found the issue.

"The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method."

In other words, the server doesn't support application/json.

I just removed these two lines and it worked...

[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];