Calendar method; Get first monday and first day of year helper

CalendarExtension.swift

import Foundation

extension Calendar {
	
	static func australia() -> Calendar {
		var calendar = Calendar(identifier: .gregorian)
		calendar.timeZone = TimeZone(abbreviation: "UTC")!
		calendar.locale = Locale(identifier: "en_AU")
		return calendar
	}
	
	/// Get a monday of current week.
	///
	/// - Parameter date: A date of week you need to get Monday. It's an optional parameter and default set as today.
	///
	/// - Returns: A date object of Monday for current week or nil if cannot get a first date from calendar.
	///
	/// Notes: reference https://stackoverflow.com/a/27044983/150768.
	
	func firstMonday(inAWeekOf date: Date = Date()) -> Date? {
		var dateComps = dateComponents([.weekOfYear, .year, .month, .weekday], from: date)
		dateComps.weekday = 2
		return self.date(from: dateComps)
	}
	
	/// Get a first day of current year.
	///
	/// - Parameter date: A date of year you need to get first day. It's an optional parameter and default set as today
	///
	/// - Returns: A date object at 1 Jan of current year or nil if cannot get a first date from calendar.
	
	func firstDayOfYear(inAYearOf date: Date = Date()) -> Date? {
		var dateComps = dateComponents([.weekdayOrdinal, .year, .month, .day], from: date)
		dateComps.month = 1
		dateComps.day = 1
		return self.date(from: dateComps)
	}
}