swift - 查询中的向下转换错误

我正在尝试使用查询删除对象。但是我收到一个向下转换错误，说[PFObject]的向下转换仅解包了您要使用的可选选项！

 var query: PFQuery = PFQuery(className: "Posts")
    query.whereKey("deleteID", containsString: selectedObjId)

    query.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
        for object in (objects as! [PFObject]) {

            if error == nil {
                //Hide activity indicator and go back to collection view when done deleting
                object.delete() // 削除
                self.hideActivityIndicator(self.view)
                self.quitButtonPressed()

            }
        }
    }

最佳答案

似乎返回的objects是[PFObject]?类型的，所以不用向下转换，只需解开对象即可

query.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
   if error == nil {
      for object in objects! {
         do {
           //Hide activity indicator and go back to collection view when done deleting
           try object.delete() // 削除
         } catch let error as NSError {
           print(error)
         }
      }
      self.hideActivityIndicator(self.view)
      self.quitButtonPressed()
  } else {
    print(error!)
  }
}

您还应该在重复循环之前检查错误是否为零，并且应该在重复循环之后执行一次隐藏指示器并按下按钮的行。

关于swift - 查询中的向下转换错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/33756934/