How To Fix Encoding Problem ?

Hi!

I'm using phpexcel extension . I have an error with my array data. The data includes turkish characters. I can download my sheet but it's not opening and it says format error. How can i fix the problem ?

Extension : http://www.yiiframework.com/extension/phpexcel

My Code :

        $data = array(
            1 => array ('İSİM', 'SOYİSİM'),
            array('İŞÇÖ', 'ÇŞÖŞÜĞ')
        );
 
        Yii::import('application.extensions.phpexcel.JPhpExcel');
 
        $xls = new JPhpExcel('UTF-8', false, 'My Test Sheet');
        $xls->addArray($data);
        $xls->generateXML('my-test');