let yesterday = today . dateByAddingTimeInterval (- 86400.0 ) let thisWeek = today . dateByAddingTimeInterval (- 604800.0 ) let lastWeek = today . dateByAddingTimeInterval (- 1209600.0 ) let thisMonth = today . dateByAddingTimeInterval (- 2629743.83 ) let lastMonth = today . dateByAddingTimeInterval (- 5259487.66 ) let calendar = NSCalendar ( identifier : NSCalendarIdentifierGregorian ) let components = calendar . components ([. Year , . Month , . Day ], fromDate : today ) let ( year , month , day ) = ( components . year , components . month , components . day )