带有--data标志的PHP Curl

有人能写一个PHP脚本来重现这个linux shell命令的功能吗？

curl -X POST -u "USERNAME:PASS" '
    -H "Content-Type: application/json" '
        --data '{"aps": {"alert": "this is a message"}}' '
            https://mywebsite.com/push/service/

我想我几乎在代码中得到了它，但我不确定如何处理--data属性。

到目前为止，我的代码是这样的：

    $headers = array();
    $headers[] = "Content-Type: application/json";
    $body = '{"aps":{"alert":"this is a message"}}';
    $ch = curl_init();
    // Set the cURL options
    curl_setopt($ch, CURLOPT_URL,            "https://mywebsite.com/push/service/");
    curl_setopt($ch, CURLOPT_USERPWD,        "USERNAME:PASSWORD");
    curl_setopt($ch, CURLOPT_POST,           TRUE);
    curl_setopt($ch, CURLOPT_POSTFIELDS,     $body);
    curl_setopt($ch, CURLOPT_HTTPHEADER,     $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    // Execute post
    $result = curl_exec($ch);
    // Close connection
    curl_close($ch);
    print_r($result);