EXC_BAD_ACCESS signal causing after inserting date into sqlite

i am taking an online course on treehouse i am trying to make an app with sqlite database what i am facing is after mention these line of code the Xcode go into freeze mode with EXC_BAD_ACCESS i read many articles on stack some people said that this reason could be to release memory such as stack please notice that i am still new in IOS development.

       entry.body = self.textField.text;
       NSLog(@"Body is: %@",entry.body);
       entry.date = [[NSDate date]timeIntervalSince1970];
       NSLog(@"Date is:  %f" ,entry.date);
      [coreDataStack saveContext];