Saveinbackgroundwithblock未执行

Question

我是使用swift / Parse 的新手，并且无法更新_User中的用户列。问题是 Parse 已在运行getObjectinBackgroundWithId，saveInBackground未运行（无成功或错误）。如果我在没有按用户ID检索用户的情况下运行saveInBackgroundWithBlock，我就没有问题了。

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    var current = PFUser.currentUser().objectId
    var userId = self.dictionary[indexPath.row]["userId"]
    var query = PFQuery(className: "_User")
    var user: PFObject?
    self.query.getObjectInBackgroundWithId(userId) {
        (success: PFObject!, error: NSError!) -> Void in
        if success != nil {
            success.addUniqueObject(current, forKey: "friendRequest")
            user = success
        }
    }
    var cell = tableView.cellForRowAtIndexPath(indexPath)
    if cell?.accessoryType == UITableViewCellAccessoryType.Checkmark {
        cell?.accessoryType = UITableViewCellAccessoryType.None
    }
    else {
        self.searchController.active = false
        let alertController = UIAlertController(title: "Alert", message: "Are you sure you want to add \(cell!.textLabel!.text!) to your friends?", preferredStyle: .Alert)

        let OKAction = UIAlertAction(title: "Yes", style: .Default) { (action) in
            user!.saveInBackgroundWithBlock {
                (success: Bool!, error: NSError!) -> Void in
                if success == true {
                    println("worked")
                }
                else {
                    println(error)
                }
            }
        }
        alertController.addAction(OKAction)
        let cancelAction = UIAlertAction(title: "No", style: .Cancel) { (action) in
        }
        alertController.addAction(cancelAction)
        self.presentViewController(alertController, animated: true) {
        }
    }
}

任何帮助将不胜感激！感谢