Swift and iso8601 try parse "HH:mm:ss" - swift

Question

We used Decodable, and have a time: Date field, but from server came only time with "HH:mm:ss" format. Another date parsers with DateInRegion.
But this field crash app
I try do smth in decoder, but cant see any properties (.count)
and I dont now what need do
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .custom({ decoder -> Date in
do {
let value = try decoder.singleValueContainer()
let string = try value.decode(String.self)
if string.conut == 8 {
if let date = DateInRegion(
string: string,
format: .iso8601(options: .withTime),
fromRegion: Region.Local()
) {
return date.absoluteDate
} else {
throw DecodingError.nil
}
} else if let date = DateInRegion(
string: string,
format: .iso8601(options: .withInternetDateTime),
fromRegion: Region.Local()
) {
return date.absoluteDate
} else {
throw DecodingError.nil
}
} catch let error {

Answer 1

Not sure what you are trying to achieve, but it seems you want to handle multiple date format in a single JSON decoder.
Given the response struct is Decodable:
struct Response: Decodable {
var time: Date
var time2: Date
}
You can configure your decoder to handle all the date format you want:
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .custom({ (decoder) -> Date in
// Extract string date from the container
let container = try decoder.singleValueContainer()
let stringDate = try container.decode(String.self)
// Trying to parse the "HH:mm:ss" format
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm:ss"
if let date = dateFormatter.date(from: stringDate) {
return date // successfully parsed "HH:mm:ss" format
}
// Trying to parse the iso8601 format
if let date = ISO8601DateFormatter().date(from: stringDate) {
return date // successfully parsed iso8601 format.
}
// Unknown date format, throw an error.
let context = DecodingError.Context(codingPath: [], debugDescription: "Unable to parse a date from '\(stringDate)'")
throw DecodingError.dataCorrupted(context)
})
Note: This is an example code and it's not very optimized (DateFormatter init each time you want to parse a date, using the brute force parsing to determine whether the date is in "HH:mm:ss" format or not, ...).
I think, the best way to optimize this, is to use multiple decoders, each configured for a specific date format, and use the right one when needed. For example, if you are trying to parse a JSON from an API, you should be able to determine whether you need to parse an iso8601 format or something else, and use the right decoder accordingly.
Here is an example of the decoder working in a playground:
let json = """
{"time": "11:05:45", "time2": "2018-09-28T16:02:55+00:00"}
"""
let response = try! decoder.decode(Response.self, from: json.data(using: .utf8)!)
response.time // Jan 1, 2000 at 11:05 AM
response.time2 // Sep 28, 2018 at 6:02 PM