嗨，我在swift 2.0中收到此错误

无法调用类型为’（NSCalendarUnit，fromDate：NSDate ?, toDate：NSDate
?,选项：nil）’的参数列表的’components’

var hoy = dataFormatter.stringFromDate(NSDate())
        var despues = dataFormatter.stringFromDate(fecha)
        var calHoy = dataFormatter.dateFromString(hoy)
        var calcDesp = dataFormatter.dateFromString(despues)
        let cal = NSCalendar.currentCalendar()
        let unit:NSCalendarUnit = .Day
        let components = cal.components(unit, fromDate: calcDesp, toDate: calHoy, options: nil)