Example
NSURL *url = [NSURL URLWithString:@"http://www.example.com/"];
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
// Configure the session here.
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];
[[session dataTaskWithURL:url
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)
{
// The response object contains the metadata (HTTP headers, status code)
// The data object contains the response body
// The error object contains any client-side errors (e.g. connection
// failures) and, in some cases, may report server-side errors.
// In general, however, you should detect server-side errors by
// checking the HTTP status code in the response object.
}] resume];