Cache Label

CacheLabel.swift

    private var labelCache = [IndexPath: UILabel]()

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        ...
        if labelCache[indexPath] == nil {
            let label = UILabel()
            label.text = ...
            labelCache[indexPath] = label
        }

        let label = labelCache[indexPath]!
        cell.contentView.addSubview(label)
        ...
        return cell
    }