Wall.get php VK API, how to get username and photo?

Question

PHP

There is a code that displays photos that users have attached to posts:

<?php
$wall = file_get_contents("http://api.vk.com/method/wall.get?extended=1&owner_id=-21894049&v=5.21&filter=all&count=30"); // Отправляем запрос
$wall = json_decode($wall); // Преобразуем JSON-строку в массив
$wall = $wall->response->items; // Получаем массив
for ($i = 0; $i < count($wall); $i++) {
$x = $wall[$i]->text;
if($x !== ''){ // Не выводим пустые посты.
echo "".$wall[$i]->text."</br>"; // Выводим текст поста
$a = $wall[$i]->attachments[0]->photo->photo_604;
echo "<img src= '$a'>"; 
}}
?>

Please tell me how to display a photo and username for each post.
To display photos, I change attachments to profiles, and then I'm at a dead end. Using the poke method, I do the following:

$a = $wall[$i]->profiles[0]->id->photo_50;
  echo "<img src= '$a'>";

Does not work.
Please tell
me 1) how to "finish off" the output of the photo?
2)how to display the username?
Thank you!

Answer 1

Light up the VK API

Answer 2

read about users.get