PFQueryTableView needs a pre Query

Question

I am trying to use PFQueryTableViewController with it's default methods:

queryForTable()
tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath,
object: PFObject?) -> PFTableViewCell?

my queryForTable() looks like this:

    let userQuery = PFUser.query()
    userQuery?.whereKey("objectId", containedIn: self.groupMember)
    return userQuery!

The problem is, groupMember is a variable which value is coming from a pre-query:

        let infoQuery = PFQuery(className: "Group")
        infoQuery.whereKey("objectId", equalTo: groupIdVar!)
        infoQuery.findObjectsInBackgroundWithBlock({ (results, error) -> Void in

            self.groupMember.removeAll()

            if error != nil {
                createAlert(error!)


                return
            }
            else {
                if let results = results {


                    for result in results {


                        if let mitglieder = result["member"] as? [String] {

                            for mitglied in mitglieder {

                                self.groupMember.append(mitglied)

                            }
                            self.memberCountLbl.text = "\(self.groupMember.count)/5"
                        }
                    }}}

How can I successfully and with no great timeloss prepone the infoQuery? I tried doing the query in queryForTable() but it seems to be to "slow". Any Ideas?