日期字符串 -> 字符串日期中断？

Question

所以，我在这里看另一个问题，然后交叉：

我有 NSDate

的扩展

extension NSDate {
    private class var formatter : NSDateFormatter {
        let nsDateFormatter = NSDateFormatter()
        nsDateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss ZZZ"
        nsDateFormatter.locale = NSLocale.currentLocale()
        return nsDateFormatter
    }
    //NSString to NSDate
    public convenience init(dateString:String) {
        let dateObj = NSDate.formatter.dateFromString(dateString)!
        self.init(timeInterval: 0, sinceDate: dateObj)
    }

    //NSDate to String
    public func getString() -> String {
       return NSDate.formatter.stringFromDate(self)
    }
}

这很好用：

var date = NSDate()                       //"Feb 2, 2016, 12:36 PM"
var string = date.getString()             //"2016-02-02 12:36:11 -0500"

let copyDate = NSDate(dateString: string) //"Feb 2, 2016, 12:36 PM"
copyDate.getString()                      //"2016-02-02 12:36:11 -0500"

But if I use, for example:

"EEE, d MMM YYYY HH:mm:ss zzz" 作为日期格式：

var date = NSDate()                       //"Feb 2, 2016, 12:58 PM"
var string = date.getString()             //"Tue, 2 Feb 2016 12:58:48 GMT-5"

let copyDate = NSDate(dateString: string) //"Dec 22, 2015, 12:58 PM"
copyDate.getString()                      //"Tue, 22 Dec 2015 12:58:48 GMT-5"

为什么会这样？

它不应该像以前的情况一样工作吗？

为什么我现在有几天甚至一个月的时间中断？

Answer 1

您正在使用 capital Y for year instead of y。

Year (in "Week of Year" based calendars). This year designation is used in ISO year-week calendar as defined by ISO 8601, but can be used in non-Gregorian based calendar systems where week date processing is desired. May not always be the same value as calendar year.

将格式更改为 "EEE, d MMM yyyy HH:mm:ss zzz"

您可以在此处阅读有关 ISO 周日期的更多信息：https://en.wikipedia.org/wiki/ISO_week_date

日期字符串 -> 字符串日期中断？

Date-String -> String-Date disruption?

nsdate

nsdateformatter

ios

swift

swift2