不能使用类型为“(String, equalTo: String?!)”的参数调用 'whereKey'

Question

我在这段代码的这一行收到此错误消息：

findSweeter.whereKey("objectId", equalTo: sweet.objectForKey("sweeter")!.objectId)

错误：

cannot invoke 'whereKey' with an argument its of type '(String, equalTo: String?!)'

这是我在 cellForRowAtiIndex 路径中用来检索要在单元格中显示的个人资料图片、个人资料名称和内容的代码：

var findSweeter:PFQuery = PFUser.query()!
  findSweeter.whereKey("objectId", equalTo: sweet.objectForKey("sweeter")!.objectId)

  findSweeter.findObjectsInBackgroundWithBlock{
      (objects:[AnyObject]?, error:NSError?)->Void in

      if error == nil{
          let user:PFUser = (objects as! NSArray).lastObject as! PFUser
          cell.usernameLabel.text = user.username


          UIView.animateWithDuration(0.5, animations: {
              cell.sweetTextView.alpha = 1
              cell.timestampLabel.alpha = 1
              cell.usernameLabel.alpha = 1
              cell.profilePic.alpha  = 1
          })
      }
  }

如果能解决此问题，我们将不胜感激。使用 Xcode 6.3.2。提前致谢！

Answer 1

尝试在查询之前解包可选变量。

if let sweeter: PFObject = sweet.objectForKey("sweeter") as? PFObject {
    var findSweeter:PFQuery = PFUser.query()!
    findSweeter.whereKey("objectId", equalTo: sweeter.objectId)
    findSweeter.findObjectsInBackgroundWithBlock {
        // ...
    }
}