How to get an specific portion of script from a webpage in objective C?

How to get an specific portion of script from a webpage in objective C?

I am stuck in fetching some data from an html. I know I have to parse it
but the problem I am struggling is that I don't know how to write the
correct path (or even I don't know if it's possible) to get data from this
code:
<script type="text/javascript">
//<![CDATA[
$(function(){
var chart = new charts.QuoteChart($("#container_quote_chart"),
"EXITO",
{"precision":2,"prev_close":33300.0,"data_values":[[1377253260000,33300.0],[1377253440000,33280.0],[1377254100000,33280.0],[1377255600000,33220.0],[1377257400000,33220.0],[1377261660000,33200.0],[1377264000000,33200.0],[1377264060000,33200.0],[1377267780000,33200.0],[1377271260000,33200.0],[1377273120000,33200.0],[1377273180000,33200.0],[1377273240000,33240.0]],"exch_open_time":1377250200000,"exch_close_time":1377273600000,"show_1D":true,"selectedPeriod":"1D"});
new charts.AutoComplete(chart);
});
//]]>
</script>
The real data I need are the ones that start from "pref_close" up to
"exch_close_time".
Thanks for any help in advance.