ios - 使用其他解析查询的结果过滤解析查询不起作用 - Swift

Question

我已经在 Swift 应用程序中设置了 Parse 后端，以便我有一个关于绘画的类(class)和另一个关于用户的类(class)。

我还有一个类，其中包含指向绘画和用户的指针，以便每个用户都可以对绘画进行评分:

在我的主 TableView 中，我想加载当前登录用户已评分的所有绘画。为此，我使用以下代码:

var paintingArray: [AnyObject] = []

// Define the query that will provide the data for the table view
override func queryForTable() -> PFQuery {

    //Find User Painting Relations to display
    var relationQuery = PFQuery(className:"UserPaintingRelation")
    relationQuery.whereKey("userID", equalTo:PFUser.currentUser()!)

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

        if error == nil {
            // The find succeeded.
            // Do something with the found objects
            if let objects = objects as? [PFObject] {
                for object in objects {
                    println(object.objectId)

                    //Add the paintingID of the current object to array 
                    var paintingObjectId: AnyObject? = object["paintingID"]!.objectId
                    var paintingObjectIdString:String = paintingObjectId as! String
                    self.paintingArray.append(paintingObjectIdString)                       
                }

            }
        } else {
            // Log details of the failure
            println("Error: \(error!) \(error!.userInfo!)")
        }

    }

    //Query that loads relevant Painting objects
    var query = PFQuery(className: "Painting")
    //Make sure only the objects that are referenced in the paintingArray are loaded
    query.whereKey("objectId", containedIn: self.paintingArray)

    return query
}

此代码不会引发任何错误。但是，在模拟器中我的表格 View 似乎是空的。如果我使用正确的 PaintingID 来过滤我的查询:

query.whereKey("objectId", equalTo:"yd62zCrXR7")

而不是:

query.whereKey("objectId", containedIn: self.paintingArray)

TableView 中显示一个对象。

这让我相信第二个查询是在数组填充正确的字符串之前执行的，这导致 TableView 不加载任何对象。这个假设正确吗？如果是这样，我是否可以确保在执行第二个查询之前，paintingArray 完成从relationQuery 加载所有字符串？

非常感谢，非常感谢所有帮助!对 Swift 来说还是个新手，所以我无法真正理解到底出了什么问题。

Answer 1

按照我的评论编辑了您的代码。在您的情况下，对 userPaintingRelation 的解析调用是一个后台线程，将在后台执行，而 Paintings 查询在执行后台查询之前执行。

var paintingArray: [AnyObject] = []

// Define the query that will provide the data for the table view
override func queryForTable() -> Void {

//Find User Painting Relations to display
var relationQuery = PFQuery(className:"UserPaintingRelation")
relationQuery.whereKey("userID", equalTo:PFUser.currentUser()!)

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

    if error == nil {
        // The find succeeded.
        // Do something with the found objects
        if let objects = objects as? [PFObject] {
            for object in objects {
                println(object.objectId)

                //Add the paintingID of the current object to array 
                var paintingObjectId: AnyObject? = object["paintingID"]!.objectId
                var paintingObjectIdString:String = paintingObjectId as! String
                self.paintingArray.append(paintingObjectIdString)                       
            }
          //Query that loads relevant Painting objects
          var query = PFQuery(className: "Painting")
          //Make sure only the objects that are referenced in the paintingArray are loaded
          query.whereKey("objectId", containedIn: self.paintingArray)
          var: tableArray = query.findObjects() as [PFObject] //array for datasource of table
          yourTableView.reloadData()
        }
    } else {
        // Log details of the failure
        println("Error: \(error!) \(error!.userInfo!)")
    }

}
}