Unicode encoded value conversion

json_unicode_decode.php

<?php
    function unescapeUTF8EscapeSeq($str)
    {
        return preg_replace_callback("/\\\u([0-9a-f]{4})/i",
            create_function('$matches',
                'return html_entity_decode(\'&#x\'.$matches[1].\';\', ENT_QUOTES, \'UTF-8\');'
            ), $str);
    }

    $unicodeEncodedvalue = '\u041d\u0438\u043a\u043e\u043b\u0430\u0439 \u0420\u0435\u0448\u0438\u0442\u043a\u043e';
    var_dump(unescapeUTF8EscapeSeq($unicodeEncodedvalue));
    echo "<br/>";

    $json = '{
            "email": "s2370@example.com",
            "Hi": "\\u0416\\u0435\\u043d\\u044f",
            "socials": {
                "facebook": {
                    "identifier": "345",
                    "webSiteURL": "",
                    "profileURL": "https://www.facebook.com/app_scoped_user_id/345/",
                    "photoURL": "https://graph.facebook.com/345/picture?width=150&height=150",
                    "displayName": "Николай Решитко",
                    "description": "",
                    "firstName": "Николай",
                    "lastName": "Решитко",
                    "gender": "male",
                    "language": "ru_RU",
                    "age": null,
                    "birthDay": null,
                    "birthMonth": null,
                    "birthYear": null,
                    "email": "s2370@example.com",
                    "emailVerified": "s2370@example.com",
                    "phone": null,
                    "address": null,
                    "country": null,
                    "region": "",
                    "city": null,
                    "zip": null,
                    "username": "",
                    "coverInfoURL": "https://graph.facebook.com/345?fields=cover"
                }
            },
            "time": "2015-10-13T09:30:44-04:00"
        }';

    echo "<pre>";
    var_dump(json_decode($json, true));