json php

<?php
$servername = "servername";
$username = "username";
$password = "password";

// Create connection
$conn = mysqli_connect($servername, $username, $password, database);
$sql= "select * from notification";
$fetch = mysqli_query($conn,$sql);
$return_arr = array();
while ($row = mysqli_fetch_array($fetch, MYSQL_ASSOC)) {
    $row_array['id'] = $row['id'];
    $row_array['topic'] = $row['topic'];
    $row_array['message'] = $row['message'];
    $row_array['date'] = $row['date'];
    array_push($return_arr,$row_array);
}

$data = array(
   'item' => $return_arr
);

echo json_encode($data);
?>


https://stackoverflow.com/questions/25179668/how-to-save-and-read-array-of-array-in-nsuserdefaults-in-swift