Swift - 从 Cloudkit 公共数据库中获取所有记录

Posted 2023-02-24

【中文标题】Swift - 从 Cloudkit 公共数据库中获取所有记录

【英文标题】：Swift - Get all records from Cloudkit Public Database

【发布时间】：2018-11-24 12:15:24

【问题描述】：

您好，我正在尝试从 cloudkit 中的 publicDB 中获取所有记录，目前有超过 2000 条记录。我怎样才能将它们全部取出并将它们放入一个数组中？ 我试过这两种方法都没有成功。你能帮帮我吗？

1 方法

    let predicate = NSPredicate(value: true)
    let query = CKQuery(recordType: "Position", predicate: predicate)
    query.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]

publicDB.perform(query, inZoneWith: nil)  (results, error) -> Void in            

        if error != nil 

            DispatchQueue.main.async(execute:   () -> Void in
                self.delegate?.errorUpdating(error: error! as NSError)
                return
            )
         else 
            self.positionArray.removeAll(keepingCapacity: true)

            for record in results! 

                let position = Position(record: record as CKRecord, database: self.publicDB)
                self.positionArray.append(position)

            
        

            DispatchQueue.main.async(execute:   () -> Void in
               /* my elaboration with the complete result */
            )



    

2 方法

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

    query.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]

    let qop  = CKQueryOperation(query: query)

    qop.resultsLimit = 3000        
    qop.recordFetchedBlock =  (record: CKRecord) in
        let position = Position(record: record, database: self.publicDB)
        self.positionArray.append(position)
        print(self.positionArray.count)
    

    qop.queryCompletionBlock =  (cursor: CKQueryOperation.Cursor?, error: Error?) in
        DispatchQueue.main.async(execute:   () -> Void in
        if let cursor = cursor 

            print("entro")
            let newOperation = CKQueryOperation(cursor: cursor)

            newOperation.recordFetchedBlock = qop.recordFetchedBlock
            newOperation.queryCompletionBlock = qop.queryCompletionBlock
            self.publicDB.add(newOperation)
        

        else if let error = error 
            print("Error:", error)
        
            // No error and no cursor means the operation was successful
        else 
            print("Finished with records:", self.positionArray)
            if(!all)
                // my elaboration
            
            else
                // my elaboration
            
        
        )
    

    self.publicDB.add(qop)

使用第一种方法，我最多可以获取 100 条记录。 使用第二种方法，我最多可以获取 400 条记录。 但是我需要用所有超过 2000 条记录填充我的数组，如何才能达到结果？

【参考方案1】：

请试试这个！

var Whistle = [CKRecord] ()

func loadWhistles(completionHandler: (() -> Void)?) 
    let pred = NSPredicate(value: true)
    let sort = NSSortDescriptor(key: nomeDaTabela, ascending: ordemDaTabela)
    let query = CKQuery(recordType: "Cliente", predicate: pred)
    query.sortDescriptors = [sort]        

    let operation = CKQueryOperation(query: query)
    operation.desiredKeys = ["Name"]
    operation.resultsLimit = 2000

    var newWhistles = Whistle

    operation.recordFetchedBlock =  record in
        newWhistles.append(record)

    


    operation.queryCompletionBlock =  [unowned self] (cursor, error) in
        DispatchQueue.main.async 
            if error == nil 
                //ViewController.isDirty = false
                self.clienteRecords = newWhistles
                self.clientesTableView.reloadData()
             else 
                let ac = UIAlertController(title: "Fetch failed", message: "There was a problem fetching the list of whistles; please try again: \(error!.localizedDescription)", preferredStyle: .alert)
                ac.addAction(UIAlertAction(title: "OK", style: .default))
                self.present(ac, animated: true)
            
        
    


    PublicDatabase.add(operation)
    completionHandler?()

【参考方案2】：

确实存在每次 fetch 操作的限制为 400 条记录，因此您需要检查 查询完成块返回的 CKQueryCursor 值，如果不是 nil 则用它开始另一个操作CKQueryOperation(cursor: cursor).

所以原则上你的第二种方法是正确的。我的猜测是您的问题是由于线程问题引起的，请尝试删除DispatchQueue.main.async(execute: () -> Void in。

附：看看它是如何在RxCloudKit 中完成的（它会自动处理大数据提取），它绝对适用于提取 1000 多条记录 - RecordFetcher.queryCompletionBlock(cursor: CKQueryCursor?, error: Error?)