I have a async function within a tableview function. I want to use the result of the function in my text label. But I don't know how to wait until it's finisched

     override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = self.tableView.dequeueReusableCell(withIdentifier: "groupDetail", for: indexPath)
    let group = trainingGroups[indexPath.row]
        cell.textLabel?.text = group.name
         self.getTrainerByID(trainerId: group.trainer_id_main, completion: { [self] (isRead, err,  trainer) in
            if isRead {
             cell.detailTextLabel?.text = trainer
                trainerMain = trainer!
             }else {
                 cell.detailTextLabel?.text = "Onbekend"
      cell.detailTextLabel?.text = group.trainer_id_main
      cell.layer.masksToBounds = true
      cell.layer.borderWidth = 0.25
      cell.layer.shadowOffset = CGSize(width: -1, height: 1)
      let borderColor: UIColor =  UIColor(red: 0, green: 45/255, blue: 114/255, alpha: 1)
      cell.layer.borderColor = borderColor.cgColor
      cell.accessoryType = .disclosureIndicator
      cell.tintColor = UIColor.white

      return cell

    }

    How do I make te return of te cell wait until the getTrainerByID is finished?

    Best regards,

    Armand