如何使用 swift 在 Firestore 文档的字段中生成 null 值？

Question

I want to make a field in firestore document to be null like lastEventApproval field in the image above.

I try to create a document by using the code below

let data = ["lastEventApproval" : nil , other data here .....]
batch.setData(userDictionary, forDocument: ref)

so I want to make when I successfully create a document, there is a field called lastEventApproval and the value is null like the image above

but the result is....

that lastEventApproval doesn't exist if I use that code. like this

in Android, I can make something like that using this code

val data = hashMapOf("lastEventApproval" to null)
batch.set(ref,data)

but I don't know why it doesn't work in iOS swift, maybe I need to asign other value than nil?

so how to make a field in firestore document to be null in swift?

Answer 1

If you want to actually write a null to use as a placeholder (for example) it's just this

func writeNull() {
    let collRef = self.db.collection("test_collection")
    let data: [String: Any] = [
        "key": "value",
        "key1": NSNull()
    ]
    collRef.addDocument(data: data)
}

and the result

This also works

func writeNull() {
    let collRef = self.db.collection("test_collection")
    let data: [String: Any?] = [
        "key": "value",
        "key1": nil
    ]
    collRef.addDocument(data: data)
}