iOS: scrollToRowAtIndexPath doesn't display correct top indexpath for last page

Question

I am trying to scroll tableview programmatically as coded following. Please note that I have increased the content size so I can see few last few remaining rows. I can scroll manually correctly to get required indexpath at top but programmatically it's not happening.

[tableview reloadData];

CGSize size = tableview.contentSize;
size.height += 1000;
tableview.contentSize = size;

int rows = [tableview numberOfRowsInSection:0];
int numberofRowsInView = 17;
for (int i = 0; i < ceil((float)rows/numberofRowsInView); i++) {
    [tableview scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:i * numberofRowsInView inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:NO];
    ....
}

For total rows 60, I expect this code to return cell views of 0-16, 17-33, 34-50, 51-59 but for the last scroll it returns 43-59 i.e. full 17 rows view while based on above code, top indexpath should be 51 for the last page!

Can someone please help me to sort this out. Thanks.

This is manually scrolling image:

This is done programmatically:

Answer 1

It seems I am not going to get this working. I need last page cells only for fraction of time and then I reset back to original tableview frame.

int rows = [tableview numberOfRowsInSection:0];
int numberofRowsInView = 17;

for (int i = 0; i < ceil((float)rows/numberofRowsInView); i++) {
    NSUInteger remainingCells = rows - i*numberofRowsInView;
    if(remainingCells < numberofRowsInView) {
        CGRect frame = tableview.frame;
        frame.size.height = remainingCells * tableview.rowHeight;
        tableview.frame = frame;
    }

    [tableview scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:i * numberofRowsInView inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:NO];
     ......

  }

Now it shows exactly remained cells on last page! I don't need to set contentSize anymore.

Answer 2

If 17 rows fit on the screen then you can't scroll so that less than 17 items are shown. So, the table view will take the row that you have requested to be at the top and scroll to the nearest one that means the view is 'full' of rows. Basically it's because 60 isn't (exactly) divisible by 17 so the table view won't let you only show a half 'page'.

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Alternatively, you can try using the scroll view method setContentOffset:animated: based on the frame of the cell you want at the top (rectForRowAtIndexPath:).