Adding new cell while scrolling causes table view to jump

If you...

Swipe the tableview to scroll it fast (or slow).
Hit the '+' button while it's scrolling

... the tableview jumps up before it continues scrolling from a random location. This doesn't happen if the tableview is not scrolling (i.e. it's stationary) when you add cells. I'm assuming this is another UITableView auto-sizing bug that has something to do with scrollView frame and offset calculations when the table view is being scrolled.

Anyone have any ideas for a workaround? I wanted to check before I try to get too clever.

Turns out that if you change the addRow method to use reloadData as follows, the jumping issue disappears.

func addRow()
{
    model.addSingleItem()
    self.tableView.reloadData()
}

It certainly seems like insertRowsAtIndexPath:withRowAnimation: is the problem here because it probably attempts to adjust scrollview height immediately but by using the estimatedRowHeight of the newly inserted rows.

Calling reloadData whenever a couple of cells are added certainly seems like a less than ideal workaround, so I'm still interested to see if anyone has better ideas.

This stops the tableView from scrolling and therefore prevents the glitch:
tableView.setContentOffset(tableView.contentOffset, animated: false)

Hope it helps someone

@budidino

@budidino when do you call it?

@budidino

@budidino when do you call it?

call "tableView.setContentOffset(tableView.contentOffset, animated: false)" just before you reloadData()

https://brigade.engineering/reloading-uitableview-while-animating-scroll-in-ios-11-f89910c958b6 hope this will help somebody! I personally found it very useful while I stuck with the problem how to delete rows while scrolling.

This actually helped me (see https://forums.developer.apple.com/thread/86703)

    self.tableView.estimatedRowHeight = 0;
    self.tableView.estimatedSectionHeaderHeight = 0;
    self.tableView.estimatedSectionFooterHeight = 0;

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Adding new cell while scrolling causes table view to jump #26

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Adding new cell while scrolling causes table view to jump #26

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rainypixels commented on Jul 31, 2015

budidino commented on Nov 2, 2016

yarodevuci commented on Nov 7, 2018

tickendy commented on Nov 19, 2018

dashared commented on Jan 29, 2019

appleios commented on Dec 11, 2019

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