D8: download binary file

demo.php

<?php

/**
 * Скачивание файла.
 */
function downloadBinaryFile(File $file = NULL) {
  if (empty($file)) {
    return NULL;
  }
  
  $fileUri = $file->getFileUri();	
  $headers = [
    'Content-disposition' => 'attachment; filename="' . $file->getFilename() . '"',
  ];
		
  return new BinaryFileResponse($fileUri, 200, $headers, false);
}