swift: convert long/int64 to date - swift

Question

I want to convert 1529704800000 to a Date object but I don't get the right date. I'm getting the value out of a json. I'm converting the value on this way:
class Example: Decodable {
var id: Int64?
var date: Date?
init(json: [String: Any]) {
id = json["id"] as? Int64 ?? -1
var dateTime = (json["date"] as AnyObject? as? Int64) ?? 0
date = Date(timeIntervalSince1970: (TimeInterval(dateTime / 1000)))
}
static func fetchReportsForUser(authorId: Int64) -> [Report]? {
let urlString = "http://localhost:8080/test-application/rest/example/"
let url = URL(string: urlString)!
var examples = [Example]()
let group = DispatchGroup()
group.enter()
DispatchQueue.global(qos: .default).async {
URLSession.shared.dataTask(with: url) { (data, response, error) -> Void in
if error != nil {
print(error!)
return
}
guard let data = data else {
return
}
if(data.isEmpty) {
group.leave()
return
}
do {
examples = try JSONDecoder().decode([Example].self, from: data)
} catch let err {
print(err)
}
group.leave()
}.resume()
}
group.wait()
return examples
}
}
When I do it like that I still get 50472-09-04 16:00:00 +0000 as date. I tried it with Double instead of Int64 but I got the same result.

Answer 1

Just let JSONDecoder do the job by using the appropriate date decoding strategy
let json = """
{"id" : 1, "date" : 1529704800000}
"""
struct Example : Decodable {
let id : Int
let date : Date
}
let data = Data(json.utf8)
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .millisecondsSince1970
do {
let result = try decoder.decode(Example.self, from: data)
print(result) // Example(id: 1, date: 2018-06-22 22:00:00 +0000)
} catch {
print(error)
}
Note: Don't make an asynchronous task synchronous. Learn to understand asynchronous data processing and use a completion handler.

Answer 2

Your integer seems to represent milliseconds rather than seconds, this it is giving a date thousands of years in the future!
Dividing it by 1000 (removing the last 3 zeros) gives 22 June 2018 10pm UTC.
Also, try changing the lines where you cast from the json to a date:
if let dateTime = json["date"] as? Int {
date = Date(timeIntervalSince1970: dateTime/1000)
}