ios - Swift CloudKit 保存记录 "Error saving record"

Question

我正在尝试将记录保存到 CloudKit 但出现错误。我在别处看到这是一个需要知道如何保存的问题，但我无法解决这个问题。

    var database:CKDatabase = CKContainer.defaultContainer().publicCloudDatabase
    var aRecord:CKRecord!

    if self.cloudId == nil {
        var recordId:CKRecordID = CKRecordID(recordName: "RecordId")
        self.cloudId = recordId // Setup at top
    }

    aRecord = CKRecord(recordType: "RecordType", recordID: self.cloudId)
    aRecord.setObject(self.localId, forKey: "localId")

    // Set the normal names etc
    aRecord.setObject(self.name, forKey: "name")

    var ops:CKModifyRecordsOperation = CKModifyRecordsOperation()
    ops.savePolicy = CKRecordSavePolicy.IfServerRecordUnchanged

    database.addOperation(ops)
    database.saveRecord(aRecord, completionHandler: { (record, error) in

        if error != nil {
            println("There was an error \(error.description)!")

        } else {
            var theRecord:CKRecord = record as CKRecord
            self.cloudId = theRecord.recordID
        }
    })

这给了我错误:

There was an error <CKError 0x16d963e0: "Server Record Changed" (14/2017); "Error saving record <CKRecordID: 0x15651730; xxxxxx:(_defaultZone:__defaultOwner__)> to server: (null)"; uuid = 369226C6-3FAF-418D-A346-49071D3DD70A; container ID = "iCloud.com.xxxxx.xxxx-2">!

不确定，因为我已经添加了 CKModifyRecordsOperation。遗憾的是，Apple 的文档中没有示例。我想念那个(你在 MSDN 上得到的)。

谢谢大家!

Answer 1

可以使用 CKDatabase 的便捷方法 saveRecord: 或通过 CKModifyRecordsOperation 将记录保存到 iCloud。如果它是单个记录，您可以使用 saveRecord:，但在将其保存回 iCloud 之前需要使用 fetchRecordWithID: 获取您要修改的记录。否则，它只会让你用新的 RecordID 保存一条记录。 More here.

database.fetchRecordWithID(recordId, completionHandler: { record, error in
    if let fetchError = error {
            println("An error occurred in \(fetchError)")
        } else {
            // Modify the record
            record.setObject(newName, forKey: "name")
        } 
}


database.saveRecord(aRecord, completionHandler: { record, error in
    if let saveError = error {
            println("An error occurred in \(saveError)")
        } else {
            // Saved record
        } 
}

上面的代码只是方向正确，但不会按原样工作，因为在 fetchRecordWithID 的 completionHandler 返回时，saveRecord 已经触发。一个简单的解决方案是将 saveRecord 嵌套在 fetchRecordWithID 的 completionHandler 中。一个可能更好的解决方案是将每个调用包装在一个 NSBlockOperation 中，并将它们添加到一个 NSOperationQueue 中，saveOperation 依赖于 fetchOperation。

这部分代码用于 CKModifyRecordsOperation，如果您只更新一条记录则不需要:

var ops:CKModifyRecordsOperation = CKModifyRecordsOperation()
ops.savePolicy = CKRecordSavePolicy.IfServerRecordUnchanged
database.addOperation(ops)

如果您确实使用 CKModifyRecordsOperation，您还需要设置至少一个完成 block 并在检测到与现有记录的冲突时处理错误:

let saveRecordsOperation = CKModifyRecordsOperation()

var ckRecordsArray = [CKRecord]()
// set values to ckRecordsArray

saveRecordsOperation.recordsToSave = ckRecordsArray
saveRecordsOperation.savePolicy = .IfServerRecordUnchanged
saveRecordsOperation.perRecordCompletionBlock { record, error in
    // deal with conflicts
    // set completionHandler of wrapper operation if it's the case
}

saveRecordsOperation.modifyRecordsCompletionBlock { savedRecords, deletedRecordIDs, error in
    // deal with conflicts
    // set completionHandler of wrapper operation if it's the case
}

database.addOperation(saveRecordsOperation)

除了使用 Objective-C 的 CloudKitAtlas 演示应用程序之外，还没有太多示例代码。希望这会有所帮助。