What kind of data-model do I need to decode this kind of json date format?
Example json:
{
createdAt: "2021-01-30T22:48:00.469Z",
updatedAt: "2021-01-30T22:48:00.490Z"
}
I tried using this model but keep getting a decoding error…
struct Date: Decodable {
var createdAt: Date
var updatedAt: Date
}
First, don't name your custom type Date - it conflicts with Date of the standard library. I renamed it to DateInfo:
struct DateInfo: Decodable {
var createdAt: Date
var updatedAt: Date
}
Then, to decode the dates into Date, you need to set the dateDecodingStrategy on the JSONDecoder to choose the date format. In your example, this is a standard iso8601 format, but with fractional seconds, and (thanks to @LeoDabus) which the built-in decoding strategy .iso8601 doesn't support:
So, without fractional seconds, it would have been done like so:
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
let dateInfo = try decoder.decode(DateInfo.self, from: jsonData)
But with fractional seconds, it requires some manual work to decode and format using ISO8601DateFormatter. As a matter of convenience, we could create extensions with the custom formatter and the date decoding strategy:
extension Formatter {
static var customISO8601DateFormatter: ISO8601DateFormatter = {
let formatter = ISO8601DateFormatter()
formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
return formatter
}()
}
extension JSONDecoder.DateDecodingStrategy {
static var iso8601WithFractionalSeconds = custom { decoder in
let dateStr = try decoder.singleValueContainer().decode(String.self)
let customIsoFormatter = Formatter.customISO8601DateFormatter
if let date = customIsoFormatter.date(from: dateStr) {
return date
}
throw DecodingError.dataCorrupted(
DecodingError.Context(codingPath: decoder.codingPath,
debugDescription: "Invalid date"))
}
}
and the usage is similar to built-in strategy, except using a custom one:
decoder.dateDecodingStrategy = .iso8601WithFractionalSeconds
this is about the name that you choose, always you have to choose a different name. You can use this code to access and use data:
struct AboutDate: Codable {
let createdAt, updatedAt: String?
}
extension AboutDate {
init(data: Data) throws {
self = try newJSONDecoder().decode(AboutDate.self, from: data)
}
init(_ json: String, using encoding: String.Encoding = .utf8) throws {
guard let data = json.data(using: encoding) else {
throw NSError(domain: "JSONDecoding", code: 0, userInfo: nil)
}
try self.init(data: data)
}
init(fromURL url: URL) throws {
try self.init(data: try Data(contentsOf: url))
}
func with(
createdAt: String?? = nil,
updatedAt: String?? = nil
) -> AboutDate {
return AboutDate(
createdAt: createdAt ?? self.createdAt,
updatedAt: updatedAt ?? self.updatedAt
)
}
func jsonData() throws -> Data {
return try newJSONEncoder().encode(self)
}
func jsonString(encoding: String.Encoding = .utf8) throws -> String? {
return String(data: try self.jsonData(), encoding: encoding)
}
}
func newJSONDecoder() -> JSONDecoder {
let decoder = JSONDecoder()
if #available(iOS 10.0, OSX 10.12, tvOS 10.0, watchOS 3.0, *) {
decoder.dateDecodingStrategy = .iso8601
}
return decoder
}
func newJSONEncoder() -> JSONEncoder {
let encoder = JSONEncoder()
if #available(iOS 10.0, OSX 10.12, tvOS 10.0, watchOS 3.0, *) {
encoder.dateEncodingStrategy = .iso8601
}
return encoder
}
To use:
do {
let aboutDate = try AboutDate(json)
}
catch {
//handle err
}
You can format String to Date, after getting data
