Swift Date Checker.

DateChecker.swift

// (c) 2021 and onwards The vChewing Project (MIT License).
// ====================
// This code is released under the MIT license (SPDX-License-Identifier: MIT)

import Foundation

extension Date {
  /// Check whether current date is the given date.
  /// - Parameter dateDigits: `yyyyMMdd`, 8-digit integer. If only `MMdd`, then the year will be the current year.
  /// - Returns: The result. Will return false if the given dateDigits is invalid.
  public static func isTodayTheDate(from dateDigits: Int) -> Bool {
    let currentYear = Self.currentYear
    var dateDigits = dateDigits
    let strDateDigits = dateDigits.description
    switch strDateDigits.count {
      case 3, 4: dateDigits = currentYear * 10000 + dateDigits
      case 8:
        if let theHighest = strDateDigits.first, "12".contains(theHighest) { break }
        return false
      default: return false
    }
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyyMMdd"
    var calendar = NSCalendar.current
    calendar.timeZone = TimeZone.current
    let components = calendar.dateComponents([.day, .month, .year], from: Date())
    if let a = calendar.date(from: components), let b = formatter.date(from: dateDigits.description), a == b {
      return true
    }
    return false
  }
  
  public static var currentYear: Int {
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy"
    return (Int(formatter.string(from: Date())) ?? 1970)
  }
}

// MARK: - Tests.

NSLog("start")
print(Date.isTodayTheDate(from: 20230206))
NSLog("end")