ヘッダーを送信してイメージを取得

   NSURL* url = [NSURL URLWithString:@"hogehogehogeURL"];
    NSURLSessionConfiguration* config = [NSURLSessionConfiguration defaultSessionConfiguration];
    
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
                                                           cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                       timeoutInterval:60.0];

    [request addValue:@"hogehoge" forHTTPHeaderField:@"hogehogeHeader"];
    [request setHTTPMethod:@"GET"];
    
    NSURLSession* session = [NSURLSession sessionWithConfiguration:config];
    NSURLSessionDataTask* task = [session dataTaskWithRequest:request
               completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                   UIImage* image = [UIImage imageWithData:data];
                   NSLog(@"");
               }];
    
    [task resume];