Anyone could help me how to handle orientation change event in Javascript when visiting through uiwebview in iPhone?

I am trying to capture onorientationchange event of Javascript. I tried following code:

<style type="text/css" media="only screen and (max-device-width: 480px)">

    .portrait

    {

        width: 300px;

        padding: 0 15px 0 5px;

    }

    .landscape

    {

        width: 460px;

        padding: 0 15px 0 5px;

    }

</style>



<script type="text/javascript">

    window.onload = orientationchange;

    window.onorientationchange = orientationchange;

    function orientationchange() {

        if (window.orientation == 90

            || window.orientation == -90) {

            document.getElementById('contents').className = 'landscape';

        }

        else {

            document.getElementById('contents').className = 'portrait';

        }

    }

</script>



// and I have a div inside html



<div id="contents">

    my contents and description... e.t.c, and e.t.c...

</div>

It works fine in safari but when I visit the page using uiwebview the orientation change event is not being captured and my desired functionality could not being achieved.