uasort排序无效，请教大家，我的代码有什么问题吗？

    public function getIndustry() {

    $res = Db::name('XXXX')
        ->where(['status'=>'normal'])
        ->select();

    if (!$res) {
        return $this->ok('请求成功', []);
    }

    $industryCat1 = [];
    $industryCat2 = [];
    $industryCat3 = [];


    foreach ($res as $key => $item) {  // 记录键值
        if ($item['level'] === 1) {
            $industryCat1[$item['id']] = ['name' => $item['name'], 'weigh' => $item['weigh']];
            $industryCat2[$item['id']] = [];
        } else if ($item['level'] === 2) {
            $industryCat2[$item['pid']][$item['id']] = ['name' => $item['name'], 'weigh' => $item['weigh']];
            $industryCat3[$item['id']] = [];
        } else if ($item['level'] === 3) {
            $industryCat3[$item['pid']][$item['id']] = ['name' => $item['name'], 'weigh' => $item['weigh']];
        }
    }
// 对 industryCat1 按 weigh 降序排序
uasort($industryCat1, function ($a, $b) {
    if ($a['weigh'] == $b['weigh']) {
        return 0;
    }
    return ($a['weigh'] < $b['weigh'])? -1 : 1;
});

    $res = [
        'industryCat1' => $industryCat1,
        'industryCat2' => $industryCat2,
        'industryCat3' => $industryCat3,

    ];

    return $this->ok('请求成功', $res);
}

对 industryCat1 按 weigh 降序排序，保留键名，但是始终无法按weigh降序排序，仍然按键名升序排序，请教大家，这里是不是我写的有问题？万分感谢！