NSDateComponents返回错误的工作日

Question

如果您将运行此代码：

// January 16th 2015 10:20 AM in Amsterdam
var date = NSDate(timeIntervalSince1970: 1421400000)

var formatter = NSDateFormatter()
formatter.dateFormat = "dd-MMM"

let calendar = NSCalendar.currentCalendar()
calendar.firstWeekday = 2 // default when region == Netherlands

let units = NSCalendarUnit.YearCalendarUnit | NSCalendarUnit.MonthCalendarUnit
    | NSCalendarUnit.WeekOfMonthCalendarUnit | NSCalendarUnit.DayCalendarUnit
    | NSCalendarUnit.WeekdayCalendarUnit

// Loop days in January
for day in 1...14 {

    // select day in month
    var components = calendar.components(units, fromDate: date)
    components.day = day

    // get day and components
    let _date = calendar.dateFromComponents(components)!
    var _components = calendar.components(units, fromDate: _date)

    // retrieve characteristics
    let weekOfMonth = _components.weekOfMonth
    let dayOfWeek = _components.weekday
    let month = _components.month

    println("\(formatter.stringFromDate(_date)) is day \(dayOfWeek) of week \(weekOfMonth) of month \(month) \n")
}

你可能会回来：

01-Jan is day 5 of week 1 of month 1
02-Jan is day 6 of week 1 of month 1
03-Jan is day 7 of week 1 of month 1
04-Jan is day 1 of week 1 of month 1
05-Jan is day 2 of week 2 of month 1
06-Jan is day 3 of week 2 of month 1
07-Jan is day 4 of week 2 of month 1
.... 

那些工作日是错误的。

1月1日不仅应该是第4天（星期四），也很奇怪1月3日似乎是第1周的第7天，而1月4日似乎是同一周的第1天。

显然我在这里做错了什么，谁可以帮助我？

当您删除calendar.firstWeekday = 2线时，您将获得：

01-Jan is day 5 of week 1 of month 1
02-Jan is day 6 of week 1 of month 1
03-Jan is day 7 of week 1 of month 1
04-Jan is day 1 of week 2 of month 1
05-Jan is day 2 of week 2 of month 1
06-Jan is day 3 of week 2 of month 1
07-Jan is day 4 of week 2 of month 1
....

这更有意义，但我真的需要一周的第一天成为星期一......

我已经为您设置了一个演示项目来自己测试这种行为。 https://github.com/tiemevanveen/NSDateComponentsTest/tree/master

---

正如sha指出的那样，如果你的一周没有在sSnday上开始，components.weekday就不会改变。奇怪的是，当周一开始时，components.weekOfMonth会发生变化。

解决我的问题

如果日历的周没有从星期日开始，那么answer到另一个问题让我找到所需的工作日。

dayOfWeek = calendar.ordinalityOfUnit(.WeekdayCalendarUnit, inUnit: .WeekCalendarUnit, forDate: _date)

该代码也可用于查找月份或月份本周：

dayOfWeek = calendar.ordinalityOfUnit(.WeekdayCalendarUnit, inUnit: .WeekCalendarUnit, forDate: _date)
month = calendar.ordinalityOfUnit(.MonthCalendarUnit, inUnit: .YearCalendarUnit, forDate: _date)

Answer 1

这一切都是正确的。如果你看看Apple Documentation。你可以看到1是星期日，2 - 是星期一，依此类推。所以5是星期四的预期。