Handle 10microseconds with DateFormatter

DateTransform.swift

//
//  Created by Wanbok Choi on 2017. 5. 4..
//

import ObjectMapper
import SwiftDate

enum DateFormat: String {
  case time = "hh:mm a"
  case normal = "yyyy-MM-dd"
  case representation = "dd/MM/yy"
  case ISO8601 = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'"
  case chatSection = "dd MMM yyyy"
}

final class NewISO8601DateTransform: DateFormatterTransform {
  public init() {
    let formatter = DateFormatter()
    formatter.locale = Locale(identifier: "en_US_POSIX")
    formatter.timeZone = TimeZone(identifier: "GMT")
    formatter.dateFormat = DateFormat.ISO8601.rawValue
    
    super.init(dateFormatter: formatter)
  }
  
  override func transformFromJSON(_ value: Any?) -> Date? {
    if let dateString = value as? String {
      let date = dateFormatter.date(from: dateString)
      guard let microSecondString = dateString.components(separatedBy: ".").last,
        case let startIndex = microSecondString.index(microSecondString.startIndex, offsetBy: 3),
        case let endIndex = microSecondString.index(before: microSecondString.endIndex),
        let microSecond = Int(microSecondString.substring(with: startIndex..<endIndex))
        else { return date }
      return date?.addingTimeInterval(Double(microSecond) / 1_000_000)
    }
    return nil
  }
  
  override func transformToJSON(_ value: Date?) -> String? {
    if let date = value {
      let dateString = dateFormatter.string(from: date)
      guard let microSecondString = String(format: "%0.6f", date.timeIntervalSinceReferenceDate).components(separatedBy: ".").last,
        case let startIndex = microSecondString.index(microSecondString.endIndex, offsetBy: -3),
        case let microSecond = microSecondString.substring(from: startIndex)
        else { return dateString }
      return dateString.replacingOccurrences(of: "000Z", with: "\(microSecond)Z")
    }
    return nil
  }
}

extension Date {
  func string(format: DateFormat, isNetwork: Bool = false) -> String {
    let region = Region(tz: isNetwork ? .gmt : .current, cal: .current, loc: .englishUnitedStatesComputer)
    let dateString = self.string(format: .custom(format.rawValue), in: region)
    guard case DateFormat.ISO8601 = format,
      let microSecondString = String(format: "%0.6f", self.timeIntervalSinceReferenceDate).components(separatedBy: ".").last,
      case let startIndex = microSecondString.index(microSecondString.endIndex, offsetBy: -3),
      case let microSecond = microSecondString.substring(from: startIndex)
      else { return dateString }
    return dateString.replacingOccurrences(of: "000Z", with: "\(microSecond)Z")
  }
}

extension String {
  func date(format: DateFormat, isNetwork: Bool = false) -> Date? {
    let region = Region(tz: isNetwork ? .gmt : .current, cal: .current, loc: .englishUnitedStatesComputer)
    return self.date(format: DateFormat.custom(format.rawValue), fromRegion: region)?.absoluteDate
  }
}