Core data doesn't save character " (quotation mark) and , (comma) into data

In my iPhone app, I use the core data and XCode 7. In case user input the string and save, the character " (quotation mark) and , (comma) can't be saved via core data. Any character else can be saved. (In another iPhone app, I don't use core data, it can save " and , into sqlite database.) Please help. Thanks.