Keep timestamp label updated in UITableView - ios

Question

I have a UIViewController that has a UITableView which presents comments fetched form a live Firebase database.
Every time a new comment arrives, I call
tableView.beginUpdates()
tableView.insertRows(at: [IndexPath(row: self.liveComments.count-1, section: 0)], with: .fade)
tableView.endUpdates()
to insert the latest comment with a fade animation. This works fine.
However, each cell has a label that shows when it was posted, in the form of "seconds, minutes or hours ago". The problem is that when many comments arrive, the age label does not get updated, since the existing cells are not updated, and it looks to the user like the comment ages are wrong.
I've tried calling
tableView.reloadRows(at: self.tableView.indexPathsForVisibleRows ?? [], with: .none)
inside my tableView updated block, but the animation is all messed up, since all of the visible cells seem to get animated in a weird, "jumpy" way.
I've also tried getting all of the visible cells, and calling a method on them to update their timestamp labels manually, but I get a crash when I do this, so I guess it's not recommended:
if let visibleCells = self.tableView.visibleCells as? [LiveCommentTableViewCell] {
visibleCells.forEach { cell in
cell.updateCommentAgeLabel()
}
How can I approach this? I just need to reload all visible cells without an animation, and the last cell with a fade in animation. Thank you!

Answer 1

I would just reload all the data, as long the cellForRowAt sets the timestamp label correctly it should work fine:
// still do your nice animation
tableView.beginUpdates()
tableView.insertRows(at: [IndexPath(row: self.liveComments.count-1, section: 0)], with: .fade)
tableView.endUpdates()
// now just refresh the entire table
tableView.reloadData()
of course you're going to want to make sure that whatever collection feeds the numberOfItemsInSection is also updated before calling reloadData() im assuming you're already doing this as well or you'd be running into a lot of bugs and crashes
make sure that code that edits UI is on the main thread too, obviously.
That being said what does your cell.updateCommentAgeLabel() function look like bc that would work in theory as well unless potentially its not being called on the main thread again or the cast isn't working.
Perhaps try telling the system you want it to do a layout pass:
if let visibleCells = self.tableView.visibleCells as? [LiveCommentTableViewCell] {
visibleCells.forEach { cell in
cell.updateCommentAgeLabel()
cell.layoutIfNeeded() // either this
}
tableView.layoutIfNeeded() // OR this at the end, I dont expect you'll need to do both but not sure if both work