如何在不创建新记录的情况下更新 cloudKit 上的数据？

Question

这就是我想要做的。我有一个简单的日记应用程序，它有两个视图：一个 tableView 列出条目的标题，一个 viewController 有一个标题的文本字段，一个 textView 的文本正文（以及一个保存到 cloudKit 的保存按钮）。在 viewController 上，我点击保存，记录保存到 cloudKit 并成功添加到 tableView。这一切都很好。

我希望能够编辑/更新日记条目。但是当我回到日记条目，以任何方式更改它，然后再次点击保存，应用程序返回到 tableView 控制器并带有更新的条目，但是 cloudKit 创建了一个与我想要编辑的条目分开的新条目。然后，当我重新加载应用程序时，我的 fetchRecords 函数会获取 cloudKit 创建的任何额外记录。

问题：如何在 cloudKit 中编辑/更新现有日记条目而不创建新条目？

如果您需要其他内容来进一步澄清我的问题，请告诉我。 谢谢！

这是我的 cloudKit 函数：

import Foundation
import CloudKit

class CloudKitManager {

let privateDB = CKContainer.default().publicCloudDatabase //Since this is a journaling app, we'll make it private.

func fetchRecordsWith(type: String, completion: @escaping ((_ records: [CKRecord]?, _ error: Error?) -> Void)) {

    let predicate = NSPredicate(value: true) // Like saying I want everything returned to me with the recordType: type. This isn't a good idea if you have a massive app like instagram because you don't want all posts ever made to be loaded, just some from that day and from your friends or something.

    let query = CKQuery(recordType: type, predicate: predicate)

    privateDB.perform(query, inZoneWith: nil, completionHandler: completion) //Allows us to handle the completion in the EntryController to maintain proper MVC.
}

func save(records: [CKRecord], perRecordCompletion: ((_ record: CKRecord?, _ error: Error?) -> Void)?, completion: ((_ records: [CKRecord]?, _ error: Error?) -> Void)?) {
    modify(records: records, perRecordCompletion: perRecordCompletion, completion: completion )
}

func modify(records: [CKRecord], perRecordCompletion: ((_ record: CKRecord?, _ error: Error?) -> Void)?, completion: ((_ records: [CKRecord]?, _ error: Error?) -> Void)?) {

    let operation = CKModifyRecordsOperation(recordsToSave: records, recordIDsToDelete: nil)

    operation.savePolicy = .ifServerRecordUnchanged //This is what updates certain changes within a record.
    operation.queuePriority = .high
    operation.qualityOfService = .userInteractive

    operation.perRecordCompletionBlock = perRecordCompletion
    operation.modifyRecordsCompletionBlock = { (records, _, error) in
        completion?(records, error)
    }

    privateDB.add(operation) //This is what actually saves your data to the database on cloudkit. When there is an operation, you need to add it.

 }
}

这是我使用 cloudKit 功能的模型控制器：

import Foundation
import CloudKit

let entriesWereSetNotification = Notification.Name("entriesWereSet")

class EntryController {

private static let EntriesKey = "entries"

static let shared = EntryController()

let cloudKitManager = CloudKitManager()

init() {
    loadFromPersistentStorage()
}

func addEntryWith(title: String, text: String) {

    let entry = Entry(title: title, text: text)

    entries.append(entry)

    saveToPersistentStorage()
}

func remove(entry: Entry) {

    if let entryIndex = entries.index(of: entry) {
        entries.remove(at: entryIndex)
    }

    saveToPersistentStorage()
}

func update(entry: Entry, with title: String, text: String) {

    entry.title = title
    entry.text = text
    saveToPersistentStorage()
}

// MARK: Private

private func loadFromPersistentStorage() {
    cloudKitManager.fetchRecordsWith(type: Entry.TypeKey) { (records, error) in
        if let error = error {
            print(error.localizedDescription)
        }
        guard let records = records else { return } //Make sure there are records.

        let entries = records.flatMap({Entry(cloudKitRecord: $0)})
        self.entries = entries //This is connected to the private(set) property "entries"
    }
}

private func saveToPersistentStorage() {

    let entryRecords = self.entries.map({$0.cloudKitRecord})


    cloudKitManager.save(records: entryRecords, perRecordCompletion: nil) { (records, error) in
        if error != nil {
            print(error?.localizedDescription as Any)
            return
        } else {
            print("Successfully saved records to cloudKit")
        }
    }
}

// MARK: Properties

private(set) var entries = [Entry]() {

    didSet {
        DispatchQueue.main.async {
            NotificationCenter.default.post(name: entriesWereSetNotification, object: nil)
        }
    }
}
}

Answer 1

这里有几个主题可能会有所帮助。

如果您在本地缓存数据，您将使用 encodesystemfields 方法创建一个新的 CKRecord，该 CKRecord 将更新服务器上现有的。

How (and when) do I use iCloud's encodeSystemFields method on CKRecord?

您似乎没有在本地缓存。我没有使用 encodesystemfields 的经验，但看起来您必须将记录拉下来并将其保存回便捷方法的完成处理程序中：

Trying to modify ckrecord in swift