set aNSDate to makeNSDate(2016, 1, 1) of me
set aCal to current application’s NSCalendar’s currentCalendar()
aCal’s setMinimumDaysInFirstWeek:1
set aWN to (aCal’s components:(current application’s NSWeekCalendarUnit) fromDate:aNSDate)’s week()

aCal’s setMinimumDaysInFirstWeek:4 –ISO8601 Week Count
set bWN to (aCal’s components:(current application’s NSWeekCalendarUnit) fromDate:aNSDate)’s week()

return {aWN, bWN}
–>　　{1, 52}

–Y,M,Dを指定してNSDateを作成
on makeNSDate(aYear as integer, aMonth as integer, aDay as integer)
　　set aComp to current application’s NSDateComponents’s alloc()’s init()
　　aComp’s setDay:aDay
　　aComp’s setMonth:aMonth
　　aComp’s setYear:aYear
　　set aGrego to current application’s NSCalendar’s calendarWithIdentifier:(current application’s NSCalendarIdentifierGregorian)
　　set aDate to aGrego’s dateFromComponents:aComp
　　return aDate
end makeNSDate