iOS UItableview scrollToRowAtIndexPath not working anymore

For recent versions of iOS, please read Fyodor Volchyok's answer. Note that it's not marked as the accepted answer simply because at the time the question was first asked (Sept. 2012), the current answer was the working solution. More recent versions of iOS also got the same problem which is now solved by Fyodor Volchyok's answer, so you should +1 his answer at that moment.

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I found the answer. I have to first reload the data in the tableview

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:linePos inSection:chapterPos];

[self.tableView reloadData];

[self.tableView scrollToRowAtIndexPath:indexPath 
    atScrollPosition:UITableViewScrollPositionTop animated:YES];

Even though I found the answer I don't know why it is working in iOS5 and not in iOS6.

EDIT

Perhaps I should add that even though it was working, I was still having a problem in displaying the last row and posted a question for that

UItableview scrollToRowAtIndexPath not displaying last row correctly

As @Raj also asked for it, I should say that I was triggering that in the viewDidLoad. To correct the problem of the last row not displaying correctly I had to put it in the viewDidAppear.

Objective-C:

[self.tableView reloadData];

dispatch_async(dispatch_get_main_queue(), ^{
        NSIndexPath *rowIndexPath = [NSIndexPath indexPathForRow:3 inSection:0];
        [self.tableView scrollToRowAtIndexPath:rowIndexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
});

Swift:

tableView.reloadData()

DispatchQueue.main.async {
    let indexPath = IndexPath(row: linePos, section: chapterPos)
    self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)
}

I ran into another issue (probably a bug) with scrollToRowAtIndexPath specifically on an iPhone X running ios11. My table has a few hundred sections and in collapsed mode ~10 would fit in the visible screen. As the indexPath got deeper, the scrolling gradually fell behind.

For example, when I wanted the search to find the item in row 30, the ScrollPositionTop would have one additional row before the actual row I expect to be at the top.

And as I tested searching for deeper rows, it started falling behind even more where for say anything past 100 rows deep or so, the expected row did not even come in the visible area.

The workaround I found so far is to say animated:NO for the scrolling within dispatch_async, then it works without any glitches.

This works in iOS 12 and 13:

DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { 
    self.tableView.scrollToRow(at: IndexPath(row: 0, section: 1), at: .bottom, animated: true) 
}