如何使用非数字索引访问多维数组中的嵌套值

Question

你好我想通过我的数组并想要访问变量。但是，如果我申请foreach，它不会显示任何内容。我做错了什么。这是阵列。

Array
(
    [22-2] => Array
        (
            [-L6mhtqkhmnyuMDkKkOX] => Array
                (
                    [receiver_id] => 2
                    [sender_id] => 22
                    [sender_name] => Rider One
                    [text] => i have done my all orders from post man 1
                    [timestamp] => 04-03-2018 21:00:42
                )
 [-L6miAxk59-jvAF2K_mA] => Array
                (
                    [receiver_id] => 2
                    [sender_id] => 22
                    [sender_name] => Rider One
                    [text] => Hahaha
                    [timestamp] => 05-03-2018 01:34:09
                )

这就是我在代码中所做的。

$json_data = json_decode($response, true);

print("<pre>".print_r($json_data,true)."</pre>");

               foreach ($json_data as $key ) {

                    echo $key['22-2']['-L6mhtqkhmnyuMDkKkOX']['sender_name'].'<br>';

                }

它没有显示发件人姓名。唯一的白色空白页面正在显示