swift - 查询中出现向下错误

Question

我正在尝试使用查询删除对象。但是，我收到一个向下转型错误，指出 Downcast from [PFObject] 仅解开选项，您是否打算使用 !?

 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()

            }
        }
    }

Answer 1

返回的对象似乎是[PFObject]类型？所以不用向下转换，只需解开对象

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!)
  }
}

您还应该检查重复循环之前错误是否为零，以及隐藏指示器和按下按钮的行是否应该在重复之后执行一次循环。