<?php

$children = array(
    (object) array('name' => 'Metropolis'),
    (object) array('name' => 'Gotham'),
    (object) array('name' => 'Moscow'),
    (object) array('name' => 'Annapolis'),
    (object) array('name' => 'Chicago'),
    (object) array('name' => 'Las Vegas'),
);

function compareChildren ($a, $b) {
    return strcmp($a->name, $b->name);
}

usort($children, 'compareChildren');
print_r($children);

Array
(
    [0] => stdClass Object
        (
            [name] => Annapolis
        )

    [1] => stdClass Object
        (
            [name] => Chicago
        )

    [2] => stdClass Object
        (
            [name] => Gotham
        )

    [3] => stdClass Object
        (
            [name] => Las Vegas
        )

    [4] => stdClass Object
        (
            [name] => Metropolis
        )

    [5] => stdClass Object
        (
            [name] => Moscow
        )

)