如何使用CloudKit将记录添加到记录类型的参考列表？

Question

我有两个简单的记录类型：Artwork和Artist。作为一个孩子，Artwork可能属于一个 Artist，但是Artist可能会有多个艺术作品。

以下是与提及的记录类型相关的屏幕截图。

我可以通过以下方式为artist设置artwork：

let artistID = CKRecordID(recordName: "F297D690-888B-4B55-9FBD-27CAEF4BBD83")
let artworkID = CKRecordID(recordName: self.idTextField.text!)

self.container.publicCloudDatabase.fetchRecordWithID(artworkID, completionHandler: { artwork, error in

    if let artwork = artwork {

        artwork["artist"] = CKReference(recordID: artistID, action: CKReferenceAction.None)
        self.container.publicCloudDatabase.saveRecord(artwork, completionHandler: { artwork, error in

             print("done")
        })
    }
})

但问题是：

如何以反向关系设置关系？换句话说，如何将artworkID添加到artistID的参考列表中？

Apple说：

  

...表示对象模型中从Artist到Collection的一对多关系，将参考字段添加到Collection记录。

但是怎么做？

Answer 1

这是我找到的最简单的答案：

let artworkID = CKRecordID(recordName: self.idTextField.text!)
if let artist = artist, var artworks = artist["artworks"] as? [CKReference] {

    let reference = CKReference(recordID: artworkID, action: CKReferenceAction.None)
    if !artworks.contains(reference) {
        artworks.append(reference)
    }
    artist["artworks"] = artworks

    //here you can save your changes or do whatever it needs
}

Answer 2

问题的关键可以在Apple文档中找到...

https://developer.apple.com/library/ios/documentation/CloudKit/Reference/CKReference_class/

允许为一组记录创建循环拥有引用。

要保存包含引用的多个记录，请先保存目标记录，或使用相同的 CKModifyRecordsOperation 对象 将所有记录保存在一个操作中。

在CloudKit中设置引用的代码我确定你见过吗？

    let uniqReference = NSUUID().UUIDString
    let unqUUID = CKRecordID(recordName: uniqUUID)
    let newRecord = CKRecord(recordType: "Blah", recordID: uniqUUID)

它表示您需要使用CKModifyOperation同时保存所有记录。

func saveLeCollection(theGlob:NSURL) {

    let container = CKContainer(identifier: "Blah.com")
    let publicDB = container.publicCloudDatabase

    let uniqUUID = CKRecordID(recordName: uniqReference)
    let newRecord = CKRecord(recordType: "Blah", recordID: uniqUUID)
    let whistleAsset = CKAsset(fileURL: theImage)
    newRecord["theImage"] = whistleAsset

    newRecord.setObject(uniqUUID, forKey: "theLink")

    var localChanges:[CKRecord] = []
    localChanges.append(newRecord)

    let saveRecordsOperation = CKModifyRecordsOperation(recordsToSave: localChanges, recordIDsToDelete: records2Erase)
    saveRecordsOperation.savePolicy = .ChangedKeys
    saveRecordsOperation.perRecordCompletionBlock =  { record, error in
        if error != nil {
            dispatch_async(dispatch_get_main_queue()) {
                self.showAlert(message: error!.localizedDescription)
                print(error!.localizedDescription)
            }
        }
        // deal with conflicts
        // set completionHandler of wrapper operation if it's the case
    }
    saveRecordsOperation.modifyRecordsCompletionBlock = { savedRecords, deletedRecordIDs, error in
        if error != nil {
            dispatch_async(dispatch_get_main_queue()) {
                self.showAlert(message: error!.localizedDescription)
                print(error!.localizedDescription)
            }
        } else {
            // deal with conflictsay
            // set completionHandler of wrapper operation if it's the case

            }
        }
    }

    saveRecordsOperation.qualityOfService = .Background
    publicDB.addOperation(saveRecordsOperation)
}

如果我将ArtistID存储在我的艺术作品记录中，则每个艺术作品记录中的相同ID我都有多个＆gt;一个参考。通过我的参考列表，我有一个＆gt;很多参考，我的艺术家记录指向每个艺术作品记录。