How to display a label on the last cell only? - swift

Question

I have a chat message table view with two cells to display, depending on whom sent the message.
I want the last cell to display the time, and only the last one. When I use tableView(:willDisplay cell:forRowAt indexPath:), the last cell doesn't show anything...
How can I display the time on that last cell?
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if chatBubbles[indexPath.row].user == UserDefaultsService.shared.userID {
let cell = tableView.dequeueReusableCell(withIdentifier: CustomCell.senderCellIdentifier.rawValue, for: indexPath) as! SenderTVC
populateSenderChatBubble(into: cell, at: indexPath)
return cell
}
else {
let cell = tableView.dequeueReusableCell(withIdentifier: CustomCell.conversationCellIdentifier.rawValue, for: indexPath) as! ConversationTVC
populateConversationChatBubble(into: cell, at: indexPath)
return cell
}
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
if indexPath.row == chatBubbles.count - 1 {
// What to do in here to display the last cell time?
}
}
Here is the method that display the cell content:
func populateSenderChatBubble(into cell: SenderTVC, at indexPath: IndexPath) {
let bubble = chatBubbles[indexPath.row]
let isoDateString = bubble.date
let trimmedIsoString = isoDateString.replacingOccurrences(of: StaticLabel.dateOccurence.rawValue, with: StaticLabel.emptyString.rawValue, options: .regularExpression)
let dateAndTime = ISO8601DateFormatter().date(from: trimmedIsoString)
date = dateAndTime!.asString(style: .short)
time = dateAndTime!.asString()
if dateAndTime!.isGreaterThanDate(dateToCompare: Date()) {
dateToShow = "\(date!) \(time!)"
}
else {
dateToShow = "\(time!)"
}
cell.senderDateLabel.text = dateToShow
cell.senderConversationLabel.text = bubble.content
}

Answer 1

The cell doesn't know it's last unless you tell it, but the tableView does know who's last. With that in mind, I would add a boolean in your cell like this:
var isLastCell: Bool = false {
didSet {
// do stuff if it's the last cell
if isLastCell {
// configure for isLastCell
} else {
// configure it for !isLastCell
}
}
}
When your custom UITableViewCell class initializes, it'll be with isLastCell = false, so assume that in your configuration. Whenever the boolean is updated to true, the cell will update via the didSet.
Then, in your cellForRow method, test the indexPath to see if it's the last indexPath of the datasource, if so, cell.isLastCell = true and the didSet in the cell will trigger to do whatever adjustments you need to do.
Another thing you'll need to do with this implementation is use cellForRow to update isLastCell for not just the last cell, but the cells that aren't last, since cells are created and destroyed all the time and the last cell at one moment might not be the last cell in another.