import Foundation
/// Adds a specified number of weeks to a given Date.
///
/// - Parameters:
/// - baseDate: The original Date instance.
/// - weeks: The number of weeks to add (can also be negative to subtract).
/// - calendar: The calendar to use for date math (defaults to Calendar.current).
/// - Returns: A new Date with the added weeks, or nil if the calculation overflows or is invalid.
func addWeeksToDate(_ baseDate: Date, weeks: Int, calendar: Calendar = .current) -> Date? {
// Multiplying weeks by 7 and adding days is a robust approach for pure calendar shifts.
return calendar.date(byAdding: .day, value: weeks * 7, to: baseDate)
}
// Example usage
let calendar = Calendar.current
// Initialize a sample date: November 8, 2026
var components = DateComponents()
components.year = 2026
components.month = 11
components.day = 8
if let targetDate = calendar.date(from: components) {
let weeksToAdd = 4
// Perform the addition
if let resultDate = addWeeksToDate(targetDate, weeks: weeksToAdd, calendar: calendar) {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd"
print("Original date: \(formatter.string(from: targetDate))")
print("After adding \(weeksToAdd) weeks: \(formatter.string(from: resultDate))")
} else {
print("Error: Date calculation failed.")
}
}
/*
run:
Original date: 2026-11-08
After adding 4 weeks: 2026-12-06
*/
