https://forum.lowyat.net/topic/4032762

key.php

<?php
$transaction = [
    'id' => 1795,
    'case_number' => 'TX2015-0123',
    'property' => [
        'id' => 69134,
        'propertyType' => [
            'id' => 1,
            'name' => 'Residential'
        ],
        'address' => [
            'block' => '160',
            'street' => 'Paya Lebar Road',
            'subpremise' => '#07-05',
            'building' => 'Orion Industrial Building',
            'country_code' => 'SG'
        ],
        'askingPrice' => '2500000.00',
        'photos' => [
            [
                'url' => 'https://www.prosage.com/thumbnails/600x400F/1c93ad90-639b-4dlc-988b-b98f75364db0.jpg',
                'is_default' => 1
            ],
            [
                'url' => 'https://www.prosage.com/thumbnails/600x400F/8de99fb6-9545-4f5f-8dfc-235a57a2b8c1.jpg',
                'is_default' => 0
            ],
            [
                'url' => 'https://www.prosage.com/thumbnails/600x400F/e595918f-8b22-4250-9b29-72c1d3f5dc45.jpg',
                'is_default' => 0
            ]
        ]
    ],
];

function getValueByPath($array, $keys)
{
    // screw you, php is not javascript, stop traversing structures with "."
    $ks = explode(".", $keys);
    $v = $array;
    while (sizeof($ks)>0) {
        $k = array_shift($ks);
        if (is_array($v) && isset($v[$k])) {
            $v = $v[$k];
        } else {
            throw new Exception("No such index ".$k);
        }
    }
    return $v;
}

print_r(getValueByPath($transaction, 'property.photos.0.url'));