wp-multi-city/includes/class-term-meta.php

<?php
declare(strict_types=1);

namespace WPMultiCity;

final class TermMeta
{
    public const GROUP_KEY = 'group_wpmc_town_main_page';

    public static function register(): void
    {
        add_action('acf/init', [self::class, 'do_register']);
    }

    public static function do_register(): void
    {
        if (!function_exists('acf_add_local_field_group')) {
            return;
        }
        acf_add_local_field_group([
            'key'    => self::GROUP_KEY,
            'title'  => 'WPMultiCity / Town main page',
            'fields' => [
                [
                    'key'           => 'field_wpmc_main_page_alt',
                    'label'         => __('Главная страница для этого города', 'wp-multi-city'),
                    'name'          => 'main_page_alt',
                    'type'          => 'post_object',
                    'post_type'     => ['page'],
                    'return_format' => 'id',
                    'allow_null'    => 1,
                    'multiple'      => 0,
                ],
            ],
            'location'   => [
                [['param' => 'taxonomy', 'operator' => '==', 'value' => 'town']],
            ],
            'menu_order' => 0,
            'position'   => 'normal',
            'style'      => 'default',
            'active'     => true,
        ]);
    }
}