SWIFT 2 - Percent Encoding not saved in JSON

Question

I am trying to post comment using 'Percent Encoding', everything seems to work however, when the php file save the value to a JSON list the encoding is changed to "\u2764\ufe0f".

Why is this happening? Should not JSON index the data as a string?

Swift:

let emo = "%E2%9D%A4%EF%B8%8F"
emo.stringByRemovingPercentEncoding  // ♥

Alamofire.request(
        .POST,
        "https://example.com/test.php?MyComment=\(emo)",  parameters: ["":""])

PHP:

    $results = array ( array( 
        "MyComment" => $MyComment
        ));

        $inp = file_get_contents('Test.json');
        $arr = json_decode($inp);
        $results = array_merge($results, $arr);

        $fp_login = fopen('Test.json', w);
        fwrite($fp_login, json_encode($results));
        fclose($fp_login);

echo $results // [{"MyComment":"\u2764\ufe0f"}]

should be saved as [{"MyComment":"%E2%9D%A4%EF%B8%8F"}]