ssa_array_objects.php

<?php 

$arrayOfObjects = [
    [
        'id' => 10,
        'name' => 'John',
        'age' => 20
    ],
    [
        'id' => 2,
        'name' => 'Jane',
        'age' => 21
    ],
    [
        'id' => 3,
        'name' => 'Jack',
        'age' => 22
    ],
    [
        'id' => 4,
        'name' => 'Kashif',
        'age' => 26
    ]
];

function sortArrayOfObjects($sort = 'DESC') : void {
    global $arrayOfObjects;

    usort($arrayOfObjects, function($a, $b) use ($sort)
    {
        return $sort == 'DESC' ? ($a['age'] < $b['age']) : ($a['age'] > $b['age']);
    });
}

function getObjectsAge() {
    global $arrayOfObjects;
    sortArrayOfObjects('ASC');

    $result = array_map(function($item){
        return $item['age'];
    }, $arrayOfObjects);

    return $result;
}

function convertObjectsToArray()
{
    global $arrayOfObjects;
    $keys = getObjectsAge();
    $result = array();

    foreach ($arrayOfObjects as $key => $item)
    {
        $result[$keys[$key]] = $item;
    }

    return $result;
}

sortArrayOfObjects('DESC');
$result = convertObjectsToArray();

print_r($result);