- array_reverse: documentation ( source)
- var_export: documentation ( source)
<?php
$array = [
2 => (object)['title' => 'Section', 'linked' => 1],
1 => (object)['title' => 'Sub-Section', 'linked' => 1],
0 => (object)['title' => 'Sub-Sub-Section', 'linked' => null]
];
$array = array_reverse( $array );
$array = array_reverse( $array );
var_export($array);