SequenceOf<T>とGeneratorOf<T>を使う

datesMatchingComponents.swift

import Foundation

func dates(#matchingComponents: NSDateComponents, var startDate: NSDate = NSDate(), endDate: NSDate = NSDate.distantFuture() as! NSDate) -> SequenceOf<NSDate> {
    return SequenceOf<NSDate> { _ -> GeneratorOf<NSDate> in
        let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
        calendar.timeZone = NSTimeZone(forSecondsFromGMT: 0)
        return GeneratorOf<NSDate> {
            if let nextDate = calendar.nextDateAfterDate(startDate, matchingComponents: matchingComponents, options: .MatchStrictly)
                where nextDate.compare(endDate) != .OrderedDescending {
                startDate = nextDate
                return startDate
            }
            return nil
        }
    }
}

今日から100年以内の2月29日を列挙.swift

let calendar = NSCalendar.currentCalendar()

let components = NSDateComponents()
components.month = 2
components.day = 29
let hundredYearsLater = calendar.dateByAddingUnit(.CalendarUnitYear, value: 100, toDate: NSDate(), options: nil)

for feb29 in dates(matchingComponents: components, startDate: NSDate(), endDate: hundredYearsLater!) {
    println(feb29)
}