如何获取current/last年的天数

Question

我想找出今年和去年的天数。我设法想出了这段代码，它将给我一个开始和结束日期。

然后我使用 NSDateComponents 来获取今年的天数。但是我得到的是365，这意味着是去年的天数。

如何正确获取去年和当年的天数？

 func numOfDaysInYear() {
        let calendar = NSCalendar.currentCalendar()
        var interval = NSTimeInterval(0)
        var startOfYear: NSDate?
        var endOfYear: NSDate!
        calendar.rangeOfUnit(.Year, startDate: &startOfYear, interval: &interval, forDate: NSDate())
        endOfYear = startOfYear?.dateByAddingTimeInterval(interval - 1)


        let comp = calendar.components(.Day, fromDate: startOfYear!, toDate: endOfYear, options: .MatchFirst)
        print(comp.day)
    }

Answer 1

 endOfYear = startOfYear?.dateByAddingTimeInterval(interval - 1)

给出当前年份内的一个日期，它与 startOfYear 是 365 天 23 小时 59 秒，因此结果是 365。

你要的是

let startOfNextYear = startOfYear!.dateByAddingTimeInterval(interval)
let comp = calendar.components(.Day, fromDate: startOfYear!, toDate: startOfNextYear, options: .MatchFirst)
print(comp.day)

给出闰年 2016 的正确输出 366。

要获得上一年的结果，只需替换当前数据 NSDate() 日期 "one year ago":

calendar.dateByAddingUnit(.Year, value: -1, toDate: NSDate(), options: [])

Answer 2

替代方法

let calendar = NSCalendar.currentCalendar()
let components = NSDateComponents()
components.day = 1
components.month = 1
let nextFirstJanuar = calendar.nextDateAfterDate(NSDate(), matchingComponents: components, options: .MatchNextTime)!
let thisFirstJanuar = calendar.nextDateAfterDate(nextFirstJanuar, matchingComponents: components, options: [.MatchNextTime, .SearchBackwards])!
let lastFirstJanuar = calendar.nextDateAfterDate(thisFirstJanuar, matchingComponents: components, options: [.MatchNextTime, .SearchBackwards])!

let daysInThisYear = calendar.components(.Day, fromDate: thisFirstJanuar, toDate: nextFirstJanuar, options: []).day
let daysInLastYear = calendar.components(.Day, fromDate: lastFirstJanuar, toDate: thisFirstJanuar, options: []).day

如何获取current/last年的天数

How to get the number of days of current/last year

nsdate

ios

swift