ios UITableview refresh a cell or section

//一个section刷新   
NSIndexSet *indexSet=[[NSIndexSet alloc]initWithIndex:2];   
[tableview reloadSections:indexSet withRowAnimation:UITableViewRowAnimationAutomatic];   
//一个cell刷新   
NSIndexPath *indexPath=[NSIndexPath indexPathForRow:3 inSection:0];   
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath,nil] withRowAnimation:UITableViewRowAnimationNone];