iOS 刷新tableView 的某一组cell或者某一行cell
//一个section刷新
NSIndexSet *indexSetTT = [[NSIndexSet alloc]initWithIndex:2]; //刷新第2组
[tableview reloadSections:indexSetTT withRowAnimation:UITableViewRowAnimationAutomatic];
//一个cell刷新
NSIndexPath *indexPathTT = [NSIndexPath indexPathForRow:2 inSection:0]; //刷新第0段第2行
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPathTT,nil] withRowAnimation:UITableViewRowAnimationNone];