XML Helper (from/to array)

Xml.php

<?php

use SimpleXMLElement;

class Xml {

    /**
     * @param  array $data
     * @param  string $root
     * @return SimpleXMLElement
     */
    public static function fromArray(array $data, $root = 'xml') : SimpleXMLElement
    {
        $xmlData = sprintf('<?xml version="1.0" encoding="UTF-8"?><%s/>', $root);
        $xml = new SimpleXMLElement($xmlData);

        static::arrayToXml($data, $xml);

        return $xml;
    }

    /**
     * @param  string $xmlString
     * @return array
     */
    public static function toArray($xmlString) : array
    {
        $xml = simplexml_load_string($xmlString, null, LIBXML_NOCDATA);

        return json_decode(json_encode($xml), true);
    }

    public static function prettyPrint($xml) : string
    {
        if ($xml instanceof SimpleXMLElement) {
            $xml = $xml->asXML();
        }

        $domxml = new \DOMDocument('1.0');
        $domxml->preserveWhiteSpace = false;
        $domxml->formatOutput = true;
        $domxml->loadXML($xml);

        return $domxml->saveXML();
    }

    /**
     * @param array $data
     * @param SimpleXMLElement $xml
     */
    private static function arrayToXml(array $data, SimpleXMLElement $xml)
    {
        foreach($data as $key => $value) {
            if(is_array($value)) {
                if (!is_numeric(key($value))) {
                    $value = [$value];
                }
                // For numeric items, add each as the same key
                foreach ($value as $childValue) {
                    if (is_array($childValue)) {
                        static::arrayToXml($childValue, $xml->addChild($key));
                    } else {
                        $xml->addChild($key, htmlspecialchars($childValue, ENT_XML1, 'UTF-8'));
                    }
                }
            } else {
                $xml->$key = $value;
            }
        }
    }
}