ios - 如何在 Swift 中从当年的每个月中获取一半

Question

在我的应用程序中，我可以选择每 15 天输入一次数据。我必须在当年维护它。请帮我解决这个问题。例如:[ “1-1-2018 至 15-1-2018”、“16-1-2018 至 31-1-2018”、 “1-2-2018 至 15-2-2018”、“16-2-2018 至 28-2-2018”、 “1-3-2018 至 15-3-2018”、“16-3-2018 至 31-3-2018”、 “1-4-2018 至 15-4-2018”、“16-4-2018 至 30-4-2018”、 “1-5-2018 至 15-5-2018”、“16-5-2018 至 31-5-2018”、 “1-6-2018 至 15-6-2018”、“16-6-2018 至 30-6-2018”、 “1-7-2018 至 15-7-2018”、“16-7-2018 至 31-7-2018”、 “1-8-2018 至 15-8-2018”、“16-8-2018 至 31-8-2018”、 “1-9-2018 至 15-9-2018”、“16-9-2018 至 30-9-2018”、 “1-10-2018 至 15-10-2018”、“16-10-2018 至 31-10-2018”、 “1-11-2018 至 15-11-2018”、“16-11-2018 至 30-11-2018”、 “1-12-2018 至 15-12-2018”、“16-12-2018 至 31-12-2018” ]

Answer 1

从 Calendar API 中，您可以获得给定日期中任何月份的总天数以及该月的第一天，如下所示，

extension Calendar {

    public func firstDayOfMonth(date: Date) -> Date {
        let components = self.dateComponents([.year, .month], from: date)
        return  self.date(from: components) ?? date
    }

    public func numberOfDaysInMonthFor(date: Date) -> Int {
        let range = self.range(of: .day, in: .month, for: date)
        return range?.count ?? 0
    }

    public func lowerHalfOfMonthFor(date: Date) -> (Date, Date) {
        let startDate = self.firstDayOfMonth(date: date)
        let endDate = startDate.dateByAppending(day: 14)

        return (startDate, endDate)
    }

    public func upperHalfOfMonthFor(date: Date) -> (Date, Date) {
        let firstDayOfMonthDate = self.firstDayOfMonth(date: date)
        let totalNoOfDaysInMonth = self.numberOfDaysInMonthFor(date: firstDayOfMonthDate)

        let startDate = firstDayOfMonthDate.dateByAppending(day: 15)
        let endDate = firstDayOfMonthDate.dateByAppending(day: totalNoOfDaysInMonth - 1)

        return (startDate, endDate)
    }
}

您还可以通过附加任意天数来扩展日期以获得新日期，

extension Date {

    public func dateByAppending(day: Int) -> Date {
        let newDate = Calendar.current.date(byAdding: .day, value: day, to: self)
        return newDate ?? self
    }

    public func daysDifference(_ date: Date?) -> Int? {
        guard let date = date else { return nil }
        return Calendar.current.dateComponents([.day], from: self, to: date).day
    }

结合使用上述辅助方法，您应该能够实现如下所示的所需结果，

let date = Date()
let lowerHalf = Calendar.current.lowerHalfOfMonthFor(date: date)
let uppperHalf = Calendar.current.upperHalfOfMonthFor(date: date)