Check the current version of an iOS app in the iTunes store

ITunes.php

<?php

/**
 * @author Corey Mcmahon <corey@foodkit.io>
 * @date: 15 January 2021
 */

declare(strict_types=1);

namespace Foodkit\AppStores;

use Illuminate\Support\Arr;
use GuzzleHttp\Client;

class ITunes
{
    private $client;

    public function __construct(Client $client)
    {
        $this->client = $client;
    }

    public function get(string $appId, string $market = '*') :? string
    {
        $response = $this->client->get($this->endpoint($appId, $market));

        $json = json_decode('' . $response->getBody(), true);

        $results = Arr::get($json, 'results', []);

        if (($count = count($results)) !== 1) {
            throw new \RuntimeException("ITunes has {$count} results for app ID {$appId}, should have 1!");
        }

        if (!($version = Arr::get($json, 'results.0.version'))) {
            throw new \RuntimeException("ITunes does not have a version # for for app ID {$appId}!");
        }

        return "{$version}";
    }

    private function endpoint(string $appId, string $market): string
    {
        $url = "https://itunes.apple.com/lookup?bundleId={$appId}";
        if ($market && $market !== '*') {
            $url .= "&country={$market}";
        }
        return $url;
    }
}