Swift - 'PFObject不能转换为NSString'

Question

我一直在尝试打印在我的PFQuery中调用的viewWillAppear，但是我从这一行得到了错误：

cell?.textLabel?.text = message as NSString as String

这是tableView cellForRowAtIndexPath的代码：

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cellId: NSString = "cell"
    var cell: UITableViewCell? = tableView.dequeueReusableCellWithIdentifier(cellId as String) as? UITableViewCell
    if (cell == nil) {
        cell = UITableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: cellId as String)
    }
    let message = myMessagesArray![indexPath.row] as! PFObject
    cell?.textLabel?.text = message as NSString as String
    return cell!
}

这是PFQuery：

 var query = PFUser.query()
    query!.orderByAscending("Messages")
    query!.findObjectsInBackgroundWithBlock {
        (objects: [AnyObject]?, error: NSError?) -> Void in
        if error == nil {
            println("Successfully retrieved (objects!.count) messages.")
            self.myMessagesArray = objects
            self.tableView?.reloadData()
        } else {
            println(error!.localizedDescription)
        }
    }