ios - dateComponents(_, from, to) 返回错误的月数

Question

我有一个创建日期的函数...

func date(withYear year: Int, month: Int, day: Int) -> Date {
    let components = DateComponents(calendar: Calendar.current, timeZone: nil, era: nil, year: year, month: month, day: day, hour: 0, minute: 0, second: 0, nanosecond: 0, weekday: nil, weekdayOrdinal: nil, quarter: nil, weekOfMonth: nil, weekOfYear: nil, yearForWeekOfYear: nil)
    return components.date!
}

为了方便起见，它只需要日、月、年。

所以我创建了两个日期。

let startDate = date(withYear: 2016, month: 9, day: 30) // prints to console as 2016-09-29 23:00:00 +0000
let endDate = date(withYear: 2016, month: 11, day: 1)   // prints to console as 2016-11-01 00:00:00 +0000

然后计算它们之间的月数...

let components = Calendar.current.dateComponents([.month], from: startDate, to: endDate)

print(components.month) // returns 1

这不应该是2吗？月份部分是如何计算的？是天数除以 30 还是别的什么？如果是这样，我需要一种新的方法来计算这里的月数。

Answer 1

我有同样的问题，但是 NSCalendar 工作正常，此代码示例证明了这一点。

    let date = NSDate()
    let calendar = NSCalendar.currentCalendar()
    let components = calendar.components([.Day , .Month , .Year], fromDate: date)

    let twoMonthdate = calendar.dateByAddingUnit(.Month, value: 2, toDate:date, options: [])

    let difference = calendar.components([.Month], fromDate: date, toDate: twoMonthdate!, options: [])
    //differences is 2 monthses

在你的情况下，差异是 1 个月零几天。这就是为什么你会收到这样的结果。