Nit: Allow date formatting to be configured by client?

[cprince-foreflight]

Is your feature request related to a problem? Please describe.
This is more of a nit than anything else, but it would be nice. Our app currently does date formatting using the ISO8601DateFormatter() configured with formatter.formatOptions.insert(.withFractionalSeconds). In this way, we get a string date with a format like:
"2023-10-04T21:41:12.000Z"

The default date formatter in Segment currently formats dates slightly differently. For example:
"2023-12-13T23:26:37.091+0000"

Describe the solution you'd like
Could date formatting be configurable by the calling client? E.g., through supplying a DateEncodingStrategy for the JSONEncoder and DateDecodingStrategy for the JSONDecoder?

[bsneed]

Hi @cprince-foreflight, yeah, definitely, it's a possibility! Though, we don't want to go that route probably as we need consistent dates across the board. Last I looked, we were getting the 000Z version you show but it has been a minute since I checked. Segment internally needs 8601 dates universally, so the options provided by JSONDecoder are more than would be desirable. If you have an idea and PR, I can probably get it merged pretty quick if it follows the 000Z format. Otherwise, it'll likely be post holidays.

[cprince-foreflight]

Looking at this more this morning, I'm realizing that the date formatting difference I'm finding has to do with using the Codable interface versus the non-Codable interface in Segment 1.5.0.

Codable interface
Default date formatting:
"2023-12-13T23:26:37.091+0000"

non-Codable interface
Default date formatting:
"2023-12-14T16:03:14.300Z"

Looking for the underlying difference in the code now.

[cprince-foreflight]

I see it now. Different date formatters are being used:

Codable
Code reference

extension DateFormatter {
    static let iso8601: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.timeZone = TimeZone(secondsFromGMT: 0)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        return formatter
    }()
}

Non-Codable
Code reference

    enum SegmentISO8601DateFormatter {
    static let shared: ISO8601DateFormatter = {
        let formatter = ISO8601DateFormatter()
        formatter.formatOptions.update(with: .withFractionalSeconds)
        return formatter
    }()

Looking into a PR to fix now.

[bsneed]

Thanks @cprince-foreflight ! Nice work, very clean! Will do a release once the gh actions finish up on main.