CKQueryOperation queryCompletionBlock返回零游标

Question

我正在用CloudKit获取一个CKQueryOperation数据库。由于某些原因，每次我按下“获取”按钮时，都会第一次得到零光标。第二次获取和获取数据时，一切都很好。当我检查recordFetchedBlock时，它确实得到了结果并追加了它们，但是在最后，数组是空的。我不明白为什么会这样。我想立即显示结果，因为他们已经被获取。我认为问题是与零光标，但我开放给其他建议。这是我的密码：

public class CloudKitDatabase {

static let shared = CloudKitDatabase()

var records = [CKRecord]()

let publicData = CKContainer.default().publicCloudDatabase

init() {
    self.fetchRecords()
}

func fetchRecords() {

    let predicate = NSPredicate(value: true)
    let query = CKQuery(recordType: "OECD", predicate: predicate)

    let queryOperation = CKQueryOperation(query: query)

    queryOperation.recordFetchedBlock = {
        record in
        self.records.append(record)


    }

    queryOperation.queryCompletionBlock = { cursor, error in
        DispatchQueue.main.async {
            if error != nil {
                print(error.debugDescription)
            } else {
                if cursor != nil {
                    self.queryServer(cursor!)
                } else {
                    print("CURSOR IS NIL")
                }
            }
        }

    }
    self.publicData.add(queryOperation)
}


func queryServer(_ cursor: CKQueryOperation.Cursor) {
    let queryOperation = CKQueryOperation(cursor: cursor)

    queryOperation.recordFetchedBlock = {
        record in
        self.records.append(record)

    }

    queryOperation.queryCompletionBlock = { cursor, error in
        DispatchQueue.main.async {
            if error != nil {
                print(error.debugDescription)
            } else {
                if cursor != nil {
                    self.queryServer(cursor!)
                } else {
                    print("CURSOR IS NIL")
                }
            }
        }
    }
    self.publicData.add(queryOperation)

}

调试区域告诉我:游标为零，CloudKitDatabase.shared.records.isEmpty为真。

Answer 1

首先，尝试一些关于第一次查询的信息；

   let queryOperation = CKQueryOperation(query: query)
   queryOperation.queuePriority = .veryHigh
   queryOperation.resultsLimit = 99 // built in limit is 400  

接下来，不要在分派中执行游标调用，并包括完成；

queryOperation.queryCompletionBlock =
{ cursor, error in

        if error != nil {
            print(error.debugDescription)
        } else {
            if cursor != nil {
                self.queryServer(cursor!)
            } else {
                print("CURSOR IS NIL")
                completion(nil)
            }
        }
}

和；

queryOperation.queryCompletionBlock = 
{ cursor, error in

        if error != nil {
            print(error.debugDescription)
        } else {
            if cursor != nil {
                self.queryServer(cursor!)
            } else {
                print("CURSOR IS NIL")
                completion(nil)
            }
        }

}

另外，不要忘记在fetchRecords开始时清空记录数组，否则连续调用将在数组中得到相同的记录。