是的，__set魔術方法在PHP中可以用于多維數組。當你嘗試為一個多維數組的元素賦值時，__set方法會被觸發。這里有一個例子來說明如何使用__set處理多維數組：

class MyArray {
    private $array;

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

    public function __set($name, $value) {
        $keys = explode('->', $name);
        $target = &$this->array;

        foreach ($keys as $key) {
            if (!isset($target[$key])) {
                $target[$key] = array();
            }
            $target = &$target[$key];
        }

        $target = $value;
    }

    public function __get($name) {
        $keys = explode('->', $name);
        $target = $this->array;

        foreach ($keys as $key) {
            if (!isset($target[$key])) {
                return null;
            }
            $target = $target[$key];
        }

        return $target;
    }
}

$myArray = new MyArray();
$myArray->user->name = 'John Doe';
$myArray->user->age = 30;
$myArray->user->address->city = 'New York';

echo $myArray->user->name; // 輸出: John Doe
echo $myArray->user->age; // 輸出: 30
echo $myArray->user->address->city; // 輸出: New York

在這個例子中，我們創建了一個名為MyArray的類，它使用__set方法來處理多維數組的賦值。當我們嘗試為$myArray->user->name、$myArray->user->age和$myArray->user->address->city賦值時，__set方法會將值存儲在相應的多維數組中。