UITableView Scrolls to Top on Cell Refresh

Question

I have a UITableView with a cell that is dynamically sized to fit a UITextView inside it. Whenever a key is typed, the cell checks to see if the calculated height has increased,

Answer 1

More simplified solution (add Notification observer when textView is changed), Swift-version. Main trick is using UIView.setAnimationsEnabled.

func textViewDidChanged(notification: NSNotification) {
    UIView.setAnimationsEnabled(false)

    let contentOffset = self.tableView.contentOffset

    tableView.beginUpdates()
    tableView.endUpdates()

    tableView.contentOffset = contentOffset

    UIView.setAnimationsEnabled(true)
}

Answer 2

Here is my UITableView extension that works perfectly. In Swift 2.1. Based on the accepted answer.

extension UITableView
{
    func reloadDataAnimatedKeepingOffset()
    {
        let offset = contentOffset
        UIView.setAnimationsEnabled(false)
        beginUpdates()
        endUpdates()
        UIView.setAnimationsEnabled(true)
        layoutIfNeeded()
        contentOffset = offset
    }
}

Answer 3

Just a guess...

Save the contentOffset of the uitableview before any changes. Then set it again after.

CGFloat contentOffset = self.tableView.contentOffset;

and then after the changes

self.tableView.contentOffset = contentOffset;

Answer 4

Wow, Josh Gafni's answer helped a lot; he deserves an upvote. My solution is based off his. This still feels like a hack, so if anyone still has a better way to do this, I'm still very interested to hear it.

First I save the content offset, then I start the update.

CGPoint offset = self.tableView.contentOffset;
[self.tableView beginUpdates];
[self.tableView endUpdates];

This animates the cell's height change and adjusts all the frames to suit the constraints.

Next I remove all animations from the tableView's layer, so the animation to the top stops. Then I reset the contentOffst to what it was before.

[self.tableView.layer removeAllAnimations];
[self.tableView setContentOffset:offset animated:NO];

Finally, I let the tableView handle the animated scroll down so the bottom of the cell is right above the keyboard.

[self.tableView scrollToRowAtIndexPath:CreateNoteCellIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

And voila, it works pretty well.