Get HTTP header fields only on iPhone

Question

I want to get only the headers of an URL request. I have been using stringWithContentsOfURL() for all downloading so far, but now I am only interested in the headers and downloading the entire file is not feasible as it is too large.

I have found solutions which show how to read the headers after the response has been receieved, but how do I specify in the request that I only wish to download headers. Skip the body!

Thanks.

Answer 1

Asynchronously send a HEAD request to the URL in question and then just access the allHeaderFields property on HTTPURLResponse / NSHTTPURLResponse.

Swift 4

var request = URLRequest(url: URL(string: "https://google.com/")!)
request.httpMethod = "HEAD"
let task = URLSession.shared.dataTask(with: request) { data, response, error in
    guard let response = response as? HTTPURLResponse,
        let headers = response.allHeaderFields as? [String: String] else {
        return
    }
}
task.resume()

Objective-C

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://google.com"]];
[request setHTTPMethod:@"HEAD"];
[NSURLConnection sendAsynchronousRequest:request
                                   queue:[NSOperationQueue mainQueue]
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
                           NSDictionary *headers = [(NSHTTPURLResponse *)response allHeaderFields];
                       }];