TableView单元内的事件性能更好

Question

I am developing a Facebook like application, where if the post is too long, it gets cut down and at the end of it "See more" appears that has some click events. (I use FRHyperLabel for it)

Everything works fine, but I've got a question: If the formatting+event is decleared inside tableView: cellForRowAt indexPath: is it bad for the performance?

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

            var message : message
            var cell : MessageCell

            let message = self.messages[indexPath.row]

            // World Message

            cell = tableView.dequeueReusableCell(withIdentifier: "essageCell", for: indexPath) as! MessageCell

            cell.messageLabel.attributedText = message.limitMessageMax250char()

            //Add link if needed
            if message.count > appSettings.maxCharacters.message {

                let handler = {
                    (hyperLabel: FRHyperLabel!, range: NSRange!) -> Void in

                    self.alert(title: "Test", message: "Alert: because clicked on link")
                }

                let text = cell.messageLabel.text!
                let nsRange = text.calculateUnicodeScalar(start: text.unicodeScalars.count-8, len: 8) // See more is 8 characters

                cell.messageLabel.setLinkFor(nsRange, withLinkHandler: handler)
            }

            return cell

    }

Or should I do it in the Cell's file, when it's awakeFromNib + with delegate

Answer 1

IMO you don't want to do this in the for cellForRowAt call mostly because you want to make that call return quickly and also because you are only returning the formatted cell.

I would argue/recommend that you set your handler for the row when it is being initialized and that way the handler value is only being set once.

Remember that cellForRowAt is called multiple times as the user scrolls through and as cells come into view.

review the https://developer.apple.com/documentation/uikit/uitableviewdatasource/1614861-tableview for more information as to how cells are reused.