正在将UTC日期格式转换为本地nsdate

Question

我从服务器上得到一个UTC时区的字符串日期，我需要将其转换为本地时区。

我的代码：

let utcTime = "2015-04-01T11:42:00.269Z"    
let dateFormatter = NSDateFormatter()
dateFormatter.timeZone = NSTimeZone(name: "UTC")
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
let date = dateFormatter.dateFromString(utcTime)
println("utc: (utcTime), date: (date)")

这个打印-

utc:2015-04-01T11:42:00.269Z，日期：可选（2015-04-01 11:42:0000）

如果我删除

dateFormatter.timeZone = NSTimeZone(name: "UTC") 

它打印

utc:2015-04-01T11:42:00.269Z，日期：可选（2015-04-01 08:42:0000）

我的本地时区是UTC+3在第一个选项中，我得到UTC在第二个选项中，我得到UTC-3

我应该得到

utc:2015-04-01T11:42:00.269Z，日期：可选（2015-04-01 14:42:0000）

那么，如何将UTC日期格式转换为本地时间呢？

Answer 1

以下内容在Objective-C中对我有效：

// create dateFormatter with UTC time format
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"]; 
[dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];
NSDate *date = [dateFormatter dateFromString:@"2015-04-01T11:42:00"]; // create date from string
// change to a readable time format and change to local time zone
[dateFormatter setDateFormat:@"EEE, MMM d, yyyy - h:mm a"];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
NSString *timestamp = [dateFormatter stringFromDate:date];

我把这两个网站放在手边，用于转换不同的时间格式：http://www.w3.org/TR/NOTE-datetime

http://benscheirman.com/2010/06/dealing-with-dates-time-zones-in-objective-c/

在Swift中，它将是：

// create dateFormatter with UTC time format
  let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
        dateFormatter.timeZone = NSTimeZone(name: "UTC") as TimeZone?
        let date = dateFormatter.date(from: "2015-04-01T11:42:00")// create   date from string
        // change to a readable time format and change to local time zone
        dateFormatter.dateFormat = "EEE, MMM d, yyyy - h:mm a"
        dateFormatter.timeZone = NSTimeZone.local
        let timeStamp = dateFormatter.string(from: date!)

Answer 2

试试这个Swift扩展

Swift 4：UTC/GMT⟺本地（当前/系统）

extension Date {
    // Convert local time to UTC (or GMT)
    func toGlobalTime() -> Date {
        let timezone = TimeZone.current
        let seconds = -TimeInterval(timezone.secondsFromGMT(for: self))
        return Date(timeInterval: seconds, since: self)
    }
    // Convert UTC (or GMT) to local time
    func toLocalTime() -> Date {
        let timezone = TimeZone.current
        let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
        return Date(timeInterval: seconds, since: self)
    }
}

// Try it
let utcDate = Date().toGlobalTime()
let localDate = utcDate.toLocalTime()
print("utcDate - (utcDate)")        //Print UTC Date
print("localDate - (localDate)")     //Print Local Date

Answer 3

c_rath答案的Swift版本：

// create dateFormatter with UTC time format
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
dateFormatter.timeZone = NSTimeZone(name: "UTC")
let date = dateFormatter.dateFromString("2015-04-01T11:42:00")
// change to a readable time format and change to local time zone
dateFormatter.dateFormat = "EEE, MMM d, yyyy - h:mm a"
dateFormatter.timeZone = NSTimeZone.localTimeZone() 
let timeStamp = dateFormatter.stringFromDate(date!)

Answer 4

我不得不从c_rath解决方案中删除z和毫秒。适用于swift 4。

extension String {
    func fromUTCToLocalDateTime() -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
        dateFormatter.timeZone = TimeZone(abbreviation: "UTC")
        var formattedString = self.replacingOccurrences(of: "Z", with: "")
        if let lowerBound = formattedString.range(of: ".")?.lowerBound {
            formattedString = "(formattedString[..<lowerBound])"
        }
        guard let date = dateFormatter.date(from: formattedString) else {
            return self
        }
        dateFormatter.dateFormat = "EEE, MMM d, yyyy - h:mm a"
        dateFormatter.timeZone = TimeZone.current
        return dateFormatter.string(from: date)
    }
}

Answer 5

在Swift 3中，运行良好

// create dateFormatter with UTC time format
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
dateFormatter.timeZone = TimeZone(abbreviation: "UTC")
let date = dateFormatter.date(from: "2015-04-01T11:42:00")// create date from string
// change to a readable time format and change to local time zone
dateFormatter.dateFormat = "EEE, MMM d, yyyy - h:mm a"
dateFormatter.timeZone = TimeZone.current
let timeStamp = dateFormatter.string(from: date!)

Answer 6

在其他人提到的基础上，这里有一个Swift 中方便的NSDate扩展

import Foundation
extension NSDate {
    func ToLocalStringWithFormat(dateFormat: String) -> String {
        // change to a readable time format and change to local time zone
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = dateFormat
        dateFormatter.timeZone = NSTimeZone.localTimeZone()
        let timeStamp = dateFormatter.stringFromDate(self)
        return timeStamp
    }
}

Answer 7

也许你可以试试这样的东西：

extension NSDate {
    convenience init(utcDate:String, dateFormat:String="yyyy-MM-dd HH:mm:ss.SSS+00:00") {
        // 2016-06-06 00:24:21.164493+00:00
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = dateFormat
        dateFormatter.timeZone = NSTimeZone(name: "UTC")
        let date = dateFormatter.dateFromString(utcDate)!
        let s = NSTimeZone.localTimeZone().secondsFromGMTForDate(date)
        let timeInterval = NSTimeInterval(s)
        self.init(timeInterval: timeInterval, sinceDate:date)
    }
}