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