var selectedDate: Date

func calendarCurrentPageDidChange(_ calendar: FSCalendar) {
        let increment = selectedDate < calendar.currentPage ? 1 : -1
        var dateToBeSelected: Date?
        switch calendar.scope {
        case .month:
            dateToBeSelected = Calendar.current.date(byAdding: .month, value: increment, to: selectedDate)
        case .week:
            dateToBeSelected = Calendar.current.date(byAdding: .weekOfYear, value: increment, to: selectedDate)
        @unknown default:
            break
        }
        calendar.select(dateToBeSelected)
        guard let _dateToBeSelected = dateToBeSelected else { return }
        selectedDate = _dateToBeSelected
    }