在Swift 4.1你可以做:

func getDate() -> Date? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
    dateFormatter.timeZone = TimeZone.current
    dateFormatter.locale = Locale.current
    return dateFormatter.date(from: "2015-04-01T11:42:00") // replace Date String
}

在Swift 4.1你可以做:

func getDate() -> Date? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
    dateFormatter.timeZone = TimeZone.current
    dateFormatter.locale = Locale.current
    return dateFormatter.date(from: "2015-04-01T11:42:00") // replace Date String
}

从iOS 15.0开始，我们可以更快速地将字符串转换为日期:

let strategy = Date.ParseStrategy(format: "\(year: .defaultDigits)-\(month: .twoDigits)-\(day: .twoDigits)T\(hour: .twoDigits(clock: .twentyFourHour, hourCycle: .zeroBased)):\(minute: .twoDigits):\(second: .twoDigits)\(timeZone: .iso8601(.short))", timeZone: .current)
let date = try? Date("2016-04-14T10:44:00+0000", strategy: strategy)

请使用ISO8601解析库来执行此操作。编码字符串的方法太多了。不要依赖于特定的格式，也不要依赖于始终发送相同的服务器。问题从末尾的“Z”开始，它将扩展到标准的所有品种。解析库将处理所有情况，并始终提供安全转换——而固定格式化字符串在将来可能会失败。

您可以使用这些库之一。CococaPods上也有:

https://github.com/boredzo/iso-8601-date-formatter/

https://github.com/malcommac/SwiftDate

看一下实现。它们都有几百行——这是有原因的。

关于这个问题:你可以使用NSDateComponents从日期中提取日期组件。网站上的例子正好符合你的情况。

https://developer.apple.com/documentation/foundation/nscalendar/1414841-components?language=objc

请注意，转换日期时会考虑到时区。你可能想显式地设置NSCalendar的locale。

只需要传递dateformate和date，就可以得到年，月，日，小时。额外的信息

func GetOnlyDateMonthYearFromFullDate(currentDateFormate:NSString , conVertFormate:NSString , convertDate:NSString ) -> NSString
    {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = currentDateFormate as String
        let formatter = NSDateFormatter()
        formatter.dateFormat = Key_DATE_FORMATE as String
        let finalDate = formatter.dateFromString(convertDate as String)
        formatter.dateFormat = conVertFormate as String
        let dateString = formatter.stringFromDate(finalDate!)

        return dateString
    }

获得一年

let Year = self.GetOnlyDateMonthYearFromFullDate("yyyy-MM-dd'T'HH:mm:ssZ", conVertFormate: "YYYY", convertDate: "2016-04-14T10:44:00+0000") as String

让月

let month = self.GetOnlyDateMonthYearFromFullDate("yyyy-MM-dd'T'HH:mm:ssZ", conVertFormate: "MM", convertDate: "2016-04-14T10:44:00+0000") as String

得到一天

let day = self.GetOnlyDateMonthYearFromFullDate("yyyy-MM-dd'T'HH:mm:ssZ", conVertFormate: "dd", convertDate: "2016-04-14T10:44:00+0000") as String

把小时

let hour  = self.GetOnlyDateMonthYearFromFullDate("yyyy-MM-dd'T'HH:mm:ssZ", conVertFormate: "hh", convertDate: "2016-04-14T10:44:00+0000") as String

那SwiftDate呢?Swift最好的日期和时间解析和操作库。

https://github.com/malcommac/SwiftDate#1-date-parsing

使用可可豆荚安装: https://github.com/malcommac/SwiftDate/blob/master/Documentation/0.Informations.md#installation

然后:

import SwiftDate

// All default datetime formats (15+) are recognized automatically
let _ = "2010-05-20 15:30:00".toDate()
// You can also provide your own format!
let _ = "2010-05-20 15:30".toDate("yyyy-MM-dd HH:mm")
// All ISO8601 variants are supported too with timezone parsing!
let _ = "2017-09-17T11:59:29+02:00".toISODate()
// RSS, Extended, HTTP, SQL, .NET and all the major variants are supported!
let _ = "19 Nov 2015 22:20:40 +0100".toRSS(alt: true)