Date+ISO8601.swift

Date+ISO8601.swift

//
//  Date+ISO8601.swift
//  SSFoundation
//
//  Created by Suyeol Jeon on 19/09/2019.
//  Copyright © 2019 StyleShare Inc. All rights reserved.
//

import Foundation

public extension Date {
  init?(iso8601String: String) {
    if let date = DateFormatter.iso8601.date(from: iso8601String) {
      self = date
    } else if let date = DateFormatter.iso8601Extended.date(from: iso8601String) {
      self = date
    } else {
      return nil
    }
  }
}

@objc public extension NSDate {
  convenience init?(iso8601String: String) {
    if let date = DateFormatter.iso8601.date(from: iso8601String) {
      self.init(timeIntervalSince1970: date.timeIntervalSince1970)
    } else if let date = DateFormatter.iso8601Extended.date(from: iso8601String) {
      self.init(timeIntervalSince1970: date.timeIntervalSince1970)
    } else {
      return nil
    }
  }
}

private extension DateFormatter {
  static let iso8601 = DateFormatter(
    format: "yyyy-MM-dd'T'HH:mm:ssZ",
    locale: "en_US_POSIX"
  )
  static  let iso8601Extended = DateFormatter(
    format: "yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ",
    locale: "en_US_POSIX"
  )

  private convenience init(format: String, locale: String) {
    self.init()
    self.dateFormat = format
    self.locale = Locale(identifier: locale)
  }
}

Date+ISO8601Spec.swift

//
//  Date+ISO8601Spec.swift
//  StyleShareTests
//
//  Created by Suyeol Jeon on 19/09/2019.
//  Copyright © 2019 StyleShare Inc. All rights reserved.
//

import SSFoundation
import SSTest

final class Date_ISO8601Spec: QuickSpec {
  override func spec() {
    describe("Date") {
      it("ISO-8601 포맷의 문자열에서 생성할 수 있습니다.") {
        expect(Date(iso8601String: "1995-01-14T12:34:56+0900")?.components) == DateComponents(year: 1995, month: 1, day: 14, hour: 12, minute: 34, second: 56)
      }

      it("밀리초가 포함된 ISO-8601 포맷의 문자열에서 생성할 수 있습니다.") {
        expect(Date(iso8601String: "1987-11-04T13:30:25.543211+0900")?.components) == DateComponents(year: 1987, month: 11, day: 4, hour: 13, minute: 30, second: 25)
      }
    }

    describe("NSDate") {
      it("ISO-8601 포맷의 문자열에서 생성할 수 있습니다.") {
        expect(NSDate(iso8601String: "1995-01-14T12:34:56+0900")?.components) == DateComponents(year: 1995, month: 1, day: 14, hour: 12, minute: 34, second: 56)
      }

      it("밀리초가 포함된 ISO-8601 포맷의 문자열에서 생성할 수 있습니다.") {
        expect(NSDate(iso8601String: "1987-11-04T13:30:25.543211+0900")?.components) == DateComponents(year: 1987, month: 11, day: 4, hour: 13, minute: 30, second: 25)
      }
    }
  }
}

private extension Date {
  var components: DateComponents? {
    // nanoseconds의 경우 부동소수점으로 인해 정확한 비교가 어렵습니다. 실제로 나노초를 비교하는 일은 없기 때문에 굳이 검증하지 않습니다.
    return Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: self)
  }
}

private extension NSDate {
  var components: DateComponents? {
    return (self as Date).components
  }
}