How to parse Firestore FieldValue to Date in Swift

Question

I am storing a document within a collection in a Cloud Firestore database. In this document, I want a reference to when the document was stored so I am using Firestore's FieldValue object which has a serverTimeStamp() function.

I am unable to parse this FieldValue object on the client as either a Date/NSDate or String. I have spent some time reading the Firestore iOS documentation and cannot find any leads on this.

There is no issue getting the FieldValue from the database to the client, however, I am unable to cast/convert the timeStamp of type FieldValue to anything.

Attempts to convert to string and date:

let timeStampString : String = message.timeStamp

let timeStampDate = Date(timeIntervalSince1970: message.timeStamp)

• Cannot assign value of type FieldValue to type String
• Cannot convert value of type FieldValue to expected argument type TimeInterval (aka Double)

Edit: After reviewing Doug Stevenson's answer, the best way to handle this is by casting your timeStamp value to a TimeStamp (not FieldValue) when reading the info on the client.

let timeStamp = document["yourTimeStampKey"] as! TimeStamp

rather than

let timeStamp = document["yourTimeStampKey"] as! FieldValue

Answer 1

There's no parsing needed. Firestore timestamp fields are of type Timestamp, which you should use directly. It represents a point in time with nanosecond precision.

Code:

let timeStamp = document["yourTimeStampKey"] as! TimeStamp

rather than

let timeStamp = document["yourTimeStampKey"] as! FieldValue