-(IBAction)addRows:(id)sender{
NSMutableArray *indexPaths = [[NSMutableArray alloc] init];
for (int i=0; i<3; i++) {
NSString *s = [[NSString alloc] initWithFormat:@”hello %d”,i];
[datas addObject:s];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:0];
[indexPaths addObject: indexPath];
}
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewScrollPositionNone];
[self.tableView endUpdates];