刷新某个section
NSIndexSet *indexSet=[[NSIndexSet alloc] initWithIndex:需要刷新的section(NSInteger)];
[tableview reloadSections:indexSet withRowAnimation:UITableViewRowAnimationAutomatic];
//刷新某一行row
NSIndexPath *indexPath=[NSIndexPath indexPathForRow:2 inSection:1]; //具体的某一行
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath,nil] withRowAnimation:UITableViewRowAnimationNone