Question

我需要为用户将一个TimeZone转换为另一个TimeZone，并且正在使用以下代码：

 let myTime = "2019-11-02 02:00:00"
 let dateFormatter = DateFormatter()
 dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
 let date = dateFormatter.date(from: myTime)
 let source_timezone = NSTimeZone(abbreviation: TimeZone.current.abbreviation()!)
 let local_timezone = NSTimeZone.system
 let source_EDT_offset = source_timezone?.secondsFromGMT(for: date!)
 let destination_EDT_offset = local_timezone.secondsFromGMT(for: date!)
 let time_interval : TimeInterval = Double(destination_EDT_offset - source_EDT_offset!)
 let final_date = NSDate(timeInterval: time_interval, since: date!)
print(final_date)

但是请在crash nil这里(source_EDT_offset)给我。

Answer 1

这里有一个代码运行方式的清理版本，请注意，在此示例中，我选择了myTime的“起始”时区

func changeToSystemTimeZone(_ date: Date, from: TimeZone, to: TimeZone = TimeZone.current) -> Date {
    let sourceOffset = from.secondsFromGMT(for: date)
    let destinationOffset = to.secondsFromGMT(for: date)
    let timeInterval = TimeInterval(destinationOffset - sourceOffset)
    return Date(timeInterval: timeInterval, since: date)
}

例如，请注意，您需要设置与输入日期（myTime的时区相匹配的语言环境

let myTime = "2019-11-02 02:00:00"
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

if let date = dateFormatter.date(from: myTime), let timeZone = TimeZone(abbreviation: "UTC") {
    let offsetedDate = changeToSystemTimeZone(date, from: timeZone)
    print(date, Calendar.current.timeZone)
    print(offsetedDate, timeZone)
}

2019-11-02 01:00:00 +0000欧洲/斯德哥尔摩（当前）
2019-11-02 02:00:00 +0000 GMT（固定）

更新：添加了用于时区的参数以转换为

将DateTime从一个时区转换为另一个时区-Swift

1 个答案: