ios - 如何正确实现Parse查询来获取有序数据

Question

我有下面的代码来从两个查询中构建一个查询。

问题是结果未按 updateAt 排序。

可能是什么问题？

let ownerQuery = PFQuery(className: "requests")
ownerQuery.whereKey("owner", equalTo: forUser)
ownerQuery.whereKey("stage", equalTo: "initiated")

let requestQuery = PFQuery(className: "requests")
requestQuery.whereKey("requested_by", equalTo: requestedBy)
requestQuery.whereKey("stage", equalTo: "accepted")

// fetch all request of current user as requestor or lender/seller
let query = PFQuery.orQuery(withSubqueries: [ownerQuery, requestQuery])

query.includeKey("requested_by")
query.includeKey("owner")
query.order(byDescending: "updatedAt")

Answer 1

问题原来是我处理检索到的数据的代码。解析返回排序结果。

我有下面的代码，其中排序受到影响。这似乎是因为 getDetails() 以异步方式返回。

所以我在返回之前添加了数组排序。我一次检索 20 行，因此我猜对每个数组进行排序应该不会很昂贵。

我还在 GitHub 上发过帖子。等待确认。

query.findObjectsInBackground { (results, error) in
            if error == nil {
                for result in results! {

                    group.enter()

                    let stage = result["stage"] as! String
                    let requestedBy = result["requested_by"] as! PFUser

                    DBHelper.getDetails(result["requested_id"] as! String, callbackFunction: { (requestedItem) in
                        let owner = result["owner"] as! PFUser
                        let request =  Request()

                        request.requestId = result.objectId
                        request.item = requestedItem

                        request.owner = owner
                       request.lastUpdatedDate = result.updatedAt
                        requestsFound.append(request)

                        group.leave()
                    }) 
                } 
                group.notify(queue: DispatchQueue.global(qos: .background), execute: {
                    DispatchQueue.main.async {
                        requestsFound.sort {(request1:Request, request2:Request) -> Bool in
                            request1.lastUpdatedDate! < request2.lastUpdatedDate!
                        }
                        callbackFunction(requestsFound,nil) 
                    }  
                })

            }  else {
                // encountered error from Parse
                DispatchQueue.main.async {

                    callbackFunction(requestsFound,error! as NSError) // to represent error at backend server

                }

            } 


            } //end of findObjectsInBackground