iOS 8 Auto Cell Height - Can't Scroll to Last Row

iOS 8 Auto cell height - Can't scroll to last row

Update: Jun 24, 2015

Apple has addressed most of these bugs as of the iOS 9.0 SDK. All of the issues are fixed as of iOS 9 beta 2, including scrolling to the top & bottom of the table view without animation, and calling reloadData while scrolled in the middle of the table view.

Here are the remaining issues that have not been fixed yet:

1. When using a large estimated row height, scrolling to the last row with animation causes the table view cells to disappear.
2. When using a small estimated row height, scrolling to the last row with animation causes the table view to finish scrolling too early, leaving some cells below the visible area (and the last row still offscreen).

A new bug report (rdar://21539211) has been filed for these issues relating to scrolling with animation.

Original Answer

This is an Apple bug with the table view row height estimation, and it has existed since this functionality first was introduced in iOS 7. I have worked directly with Apple UIKit engineers and developer evangelists on this issue -- they have acknowledged that it is a bug, but do not have any reliable workaround (short of disabling row height estimation), and did not seem particularly interested in fixing it.

Note that the bug manifests itself in other ways, such as disappearing table view cells when you call reloadData while scrolled partially or fully down (e.g. contentOffset.y is significantly greater than 0).

Clearly, with iOS 8 self sizing cells, row height estimation is critically important, so Apple really needs to address this ASAP.

I filed this issue back on Oct 21 2013 as Radar #15283329. Please do file duplicate bug reports so that Apple prioritizes a fix.

You can attach this simple sample project to demonstrate the issue. It is based directly on Apple's own sample code.

iOS - UITableView Does Not Scroll To Last Row In Data Source

I've determined that this issue has to do with cell height. By increasing tableView.estimatedRowHeight to 44.0, the table view scrolls flawlessly to the bottom. However, there remains an issue with when messages wrap beyond 1 line in a given cell. For each message longer than 1 line, the table scroll comes up a few more pixels short. Removing tableView.estimatedRowHeight altogether seems to result in similar behavior as setting it to say, 44.0. I want to say my original question is answered, but I'm still not sure how to make it scroll perfectly given the likelihood of multi-line cells.

EDIT - SOLUTION

The problem of incorrect scrolling is in fact solved by removing UITableViewAutomaticDimension and manually calculating the height in heightForRowAtIndexPath.

scrollToRowAtIndexPath doesn't handle the last row properly

Okay, I've successfully been able to fix this issue.

The clue was in this comment by Matt Di Pasquale on a semi-related question.

It turns out that in iOS 7, the views are yet to be laid out when viewWillAppear: is called, meaning the frame and bounds of the table view are not guaranteed to be accurate. Since the call to scrollToRowAtIndexPath:animated must use at least one of these to calculate the offset, this makes sense as to why in my case it wasn't being handled properly.

I think in most cases people won't encounter this issue as their presenting view controller will likely have the same bounds as the presented view controller. But in my case, I was presenting a view controller that had a visible navigation bar and status bar from one that didn't have either, ergo there was an extra 64pts to account for. As can be seen in this console output:

2014-03-15 19:14:32.129 Capture[3375:60b] viewWillAppear, tv bounds: {{0, 0}, {320, 568}}
2014-03-15 19:14:32.131 Capture[3375:60b] viewDidLayoutSubviews, tv bounds: {{0, -64}, {320, 568}}

To get around the issue, I now set a flag in viewWillAppear: that signifies there's a pending scroll and then in viewDidLayoutSubviews, if the flag is set, I call scrollToRowAtIndexPath:animated and unset the flag (since this method is called numerous times). This works flawlessly.

Hopefully this will help anyone else coming across the issue.

Scrolling to last row of table view only scrolls half way

This solution may be helpful of others with same issue.
This issue is a bug, see discussion here.

I use a footer view for adding comments to a feed so i used its height here and the tableview will scroll to the last row directly above the footer view:

self.tableView.reloadData();

            // load the last row


            let offset = CGPoint(x: 0, y: self.tableView.contentSize.height - self.tableView.frame.size.height + self.FOOTERHEIGHT);

            self.tableView.contentOffset = offset;

UITableView dynamic cell heights only correct after some scrolling

I don't know this is clearly documented or not, but adding [cell layoutIfNeeded] before returning cell solves your problem.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    TableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:@"TestCell"];
    NSUInteger n1 = firstLabelWordCount[indexPath.row];
    NSUInteger n2 = secondLabelWordCount[indexPath.row];
    [cell setNumberOfWordsForFirstLabel:n1 secondLabel:n2];

    [cell layoutIfNeeded]; // <- added

    return cell;
}

UITableview not visible the last cell when scroll down

Use -

  tableView.contentInset = UIEdgeInsetsMake(0, 0, 120, 0); //values

passed are - top, left, bottom, right

Pass bottom offset as per your needs.

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