Grab and cache JSON if it is 24 hours old

gistfile1.txt

function my_cache_get_event($id){
  $url = 'url';
  $file = __DIR__.'\cache\user_event_cache_id_'.$id.'.json';

  if (time()-filemtime($file) > 24 * 3600) {
    // file older than 24 hours
    file_put_contents($file, file_get_contents($url));
    $json = file_get_contents($file);
    return json_decode($json);
  } else {
    // file younger than 24 hours
    file_put_contents($file, file_get_contents($url));
    $json = file_get_contents($file);
    return json_decode($json);
  }

}