D8 output XML/Json

drupal8_render_Xml_or_Json.php

<?php

///////////////////JSON

//How to render Json from Drupal 8
$response = new Response();
$response->setContent(json_encode($mydata));
$response->headers->set('Content-Type', 'application/json');
return $response;


//How to render Json from drupal 8 
use Symfony\Component\HttpFoundation\JsonResponse;

return new JsonResponse($mydata);

///////////////////XML

// How to render XML from drupal 8
// This example is used in a block.

$output = '<xml></xml>';
$filename = 'output.xml';
$response = new CacheableResponse($output, Response::HTTP_OK, [
  'content-type' => 'application/xml',
  'Content-Disposition' => 'attachment;filename=' . $name,
]);

$meta_data = $response->getCacheableMetadata();
$meta_data->addCacheTags(['epg_xml', 'yout_custom_cacge_tags']);
return $response;