JSONEncoder's dateEncodingStrategy not working

Question

I am trying to serialize a struct to a String using Swift 4\'s Encodable+JSONEncoder. The object can hold heterogenous values like String, Array, Date, Int etc.

The use

Answer 1

You can eliminate the EncodableValue wrapper, and use a generic instead:

struct Bar: Encodable {
    let key: String
    let value: T?

    var json: String {
        let encoder = JSONEncoder()
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "E, d MMM yyyy"
        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
        encoder.dateEncodingStrategy = .formatted(dateFormatter)
        let data = try! encoder.encode(self)
        return String(data: data, encoding: .utf8)!
    }
}

let bar = Bar(key: "date", value: Date())

print(bar.json)

That yields:

{"key":"date","value":"Wed, 7 Feb 2018"}