ios - 如何使用 CloudKit 将记录添加到记录类型的引用列表？

Question

我有两个简单的记录类型:Artwork 和Artist。 Artwork 作为一个 child 可能属于一个 Artist，但是一个Artist 可能有多个艺术品。

以下是与上述记录类型相关的屏幕截图。

我可以通过以下方式简单地为 artwork 设置 artist:

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:

如何设置反向关系？换句话说，如何将 artworkID 添加到 artistID 的引用列表中？

苹果说:

...to represent the one-to-many relationship from Artist to Collection in the object model, add a reference field to the Collection record.

但是如何做到这一点呢？

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
}