解析大型xml文件iphone超过20 MB

i want to parse large xml file in iPhone and i have tried touch xml , gData and other xml parsers including SAX parsers .. my app crashes after parsing xml files or during parsing xmls because it keeps 40 MB of data in memory What would be the best way to parse large xml files ? i want to parse the data and insert it into core data. i want to parse large xml file in iPhone and i