Apple Snippet NSURLSession

NSURLSession.m

-(void)URLPostRequest:(NSString *)stringData success:(void (^)(id responseDict))success failure:(void (^)(NSString *error))failure {
  NSURL *url = [NSURL URLWithString:@"yoururladdresshere"]; //Set the url

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0]; // Set Timeout Interval = 1 minute

  [request setValue:@"text/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"]; // Set Charset Type
  [request addValue:@"application/json" forHTTPHeaderField:@"Accept"]; // Set Packet Type
  request.HTTPMethod = @"POST"; // Set Method

  request.HTTPBody = [stringData dataUsingEncoding:NSUTF8StringEncoding]; // Our data to Post

  // Configure Async Request
  NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
  NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:(id)self delegateQueue:nil];

  NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
  if (error) {
    failure([error localizedDescription]); // return error in completion
    return;
  } else {
    NSError *err; 
    NSDictionary *res = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&err];
    success(res);
  }];

  [postDataTask resume]; // Call Request
}