IOS: 将 UTC NSDate 转换为本地时区

如何将目标 C 或/和 Swift 中的 UTC NSDate转换为本地时区 NSDate？

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小开

将 UTC 日历中的日期 转换为具有适当本地 NSTimeZone的日期。

小开 
NSTimeInterval seconds; // assume this exists
NSDate* ts_utc = [NSDate dateWithTimeIntervalSince1970:seconds];


NSDateFormatter* df_utc = [[[NSDateFormatter alloc] init] autorelease];
[df_utc setTimeZone:[NSTimeZone timeZoneWithName:@"UTC"]];
[df_utc setDateFormat:@"yyyy.MM.dd G 'at' HH:mm:ss zzz"];


NSDateFormatter* df_local = [[[NSDateFormatter alloc] init] autorelease];
[df_local setTimeZone:[NSTimeZone timeZoneWithName:@"EST"]];
[df_local setDateFormat:@"yyyy.MM.dd G 'at' HH:mm:ss zzz"];


NSString* ts_utc_string = [df_utc stringFromDate:ts_utc];
NSString* ts_local_string = [df_local stringFromDate:ts_utc];


// you can also use NSDateFormatter dateFromString to go the opposite way

格式化字符串参数表:

Https://waracle.com/iphone-nsdateformatter-date-formatting-table/

如果性能是一个优先级，您可能需要考虑使用 strftime

Https://developer.apple.com/legacy/library/documentation/darwin/reference/manpages/man3/strftime.3.html

小开

编辑 当我写这篇文章的时候，我不知道我应该使用一个日期格式化程序，这可能是一个更好的方法，所以也可以看看 slf的答案。

我有一个以 UTC 格式返回日期的 webservice。我使用 toLocalTime转换为本地时间和 toGlobalTime转换回来，如果需要。

这就是我得到答案的地方:

Https://agilewarrior.wordpress.com/2012/06/27/how-to-convert-nsdate-to-different-time-zones/

@implementation NSDate(Utils)


-(NSDate *) toLocalTime
{
NSTimeZone *tz = [NSTimeZone defaultTimeZone];
NSInteger seconds = [tz secondsFromGMTForDate: self];
return [NSDate dateWithTimeInterval: seconds sinceDate: self];
}


-(NSDate *) toGlobalTime
{
NSTimeZone *tz = [NSTimeZone defaultTimeZone];
NSInteger seconds = -[tz secondsFromGMTForDate: self];
return [NSDate dateWithTimeInterval: seconds sinceDate: self];
}


@end
小开

这里的输入是一个字符串 currentUTCTime (格式为08/30/201211:11) ，它将 GMT 中的输入时间转换为系统设置的区域时间

//UTC time
NSDateFormatter *utcDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[utcDateFormatter setDateFormat:@"MM/dd/yyyy HH:mm"];
[utcDateFormatter setTimeZone :[NSTimeZone timeZoneForSecondsFromGMT: 0]];


// utc format
NSDate *dateInUTC = [utcDateFormatter dateFromString: currentUTCTime];


// offset second
NSInteger seconds = [[NSTimeZone systemTimeZone] secondsFromGMT];


// format it and send
NSDateFormatter *localDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[localDateFormatter setDateFormat:@"MM/dd/yyyy HH:mm"];
[localDateFormatter setTimeZone :[NSTimeZone timeZoneForSecondsFromGMT: seconds]];


// formatted string
NSString *localDate = [localDateFormatter stringFromDate: dateInUTC];
return localDate;
小开

如果需要本地日期和时间，请尝试以下代码:-

NSString *localDate = [NSDateFormatter localizedStringFromDate:[NSDate date] dateStyle:NSDateFormatterMediumStyle timeStyle:NSDateFormatterMediumStyle];
小开

我找到的最简单的方法是:

NSDate *someDateInUTC = …;
NSTimeInterval timeZoneSeconds = [[NSTimeZone localTimeZone] secondsFromGMT];
NSDate *dateInLocalTimezone = [someDateInUTC dateByAddingTimeInterval:timeZoneSeconds];
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//This is basic way to get time of any GMT time.


NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"hh:mm a"];  // 09:30 AM
[formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:1]]; // For GMT+1
NSString *time = [formatter stringFromDate:[NSDate date]];  // Current time
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因为似乎没有人使用 NSDateComponents，我想我应该投入一个..。 在这个版本中，没有使用 NSDateFormatter，因此没有字符串解析，而且 NSDate不用来表示 GMT (UTC)之外的时间。原来的 NSDate在变量 i_date中。

NSCalendar *anotherCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:i_anotherCalendar];
anotherCalendar.timeZone = [NSTimeZone timeZoneWithName:i_anotherTimeZone];


NSDateComponents *anotherComponents = [anotherCalendar components:(NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond | NSCalendarUnitNanosecond) fromDate:i_date];


// The following is just for checking
anotherComponents.calendar = anotherCalendar; // anotherComponents.date is nil without this
NSDate *anotherDate = anotherComponents.date;

i_anotherCalendar可以是 NSCalendarIdentifierGregorian或任何其他日历。 i_anotherTimeZone允许的 NSString可以通过 [NSTimeZone knownTimeZoneNames]获得，但是 anotherCalendar.timeZone可以是 [NSTimeZone defaultTimeZone]、 [NSTimeZone localTimeZone]或者 [NSTimeZone systemTimeZone]。

它实际上是 anotherComponents在新的时区保持时间。您会注意到 anotherDate等于 i_date，因为它以 GMT (UTC)表示时间。

小开

将 UTC 时间转换为当前时区。

调用函数

NSLocale *locale = [NSLocale autoupdatingCurrentLocale];


NSString *myLanguageCode = [locale objectForKey: NSLocaleLanguageCode];
NSString *myCountryCode = [locale objectForKey: NSLocaleCountryCode];


NSString *rfc3339DateTimeString = @"2015-02-15 00:00:00"];
NSDate *myDateTime = (NSDate*)[_myCommonFunctions _ConvertUTCTimeToLocalTimeWithFormat:rfc3339DateTimeString LanguageCode:myLanguageCode CountryCode:myCountryCode Formated:NO];

功能

-NSObject*)_ConvertUTCTimeToLocalTimeWithFormat:rfc3339DateTimeString     LanguageCode:(NSString *)lgc CountryCode:(NSString *)ctc Formated:(BOOL) formated
{
NSDateFormatter *sUserVisibleDateFormatter = nil;
NSDateFormatter *sRFC3339DateFormatter = nil;


NSTimeZone *timeZone = [NSTimeZone defaultTimeZone];


if (sRFC3339DateFormatter == nil)
{
sRFC3339DateFormatter = [[NSDateFormatter alloc] init];


NSLocale *myPOSIXLocale = [[NSLocale alloc] initWithLocaleIdentifier:[NSString stringWithFormat:@"%@", timeZone]];


[sRFC3339DateFormatter setLocale:myPOSIXLocale];
[sRFC3339DateFormatter setDateFormat:@"yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"];
[sRFC3339DateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
}


// Convert the RFC 3339 date time string to an NSDate.
NSDate *date = [sRFC3339DateFormatter dateFromString:rfc3339DateTimeString];


if (formated == YES)
{
NSString *userVisibleDateTimeString;


if (date != nil)
{
if (sUserVisibleDateFormatter == nil)
{
sUserVisibleDateFormatter = [[NSDateFormatter alloc] init];
[sUserVisibleDateFormatter setDateStyle:NSDateFormatterMediumStyle];
[sUserVisibleDateFormatter setTimeStyle:NSDateFormatterShortStyle];
}


// Convert the date object to a user-visible date string.
userVisibleDateTimeString = [sUserVisibleDateFormatter stringFromDate:date];


return (NSObject*)userVisibleDateTimeString;
}
}


return (NSObject*)date;
}
小开

我编写此方法将日期时间转换为 LocalTimeZone

- 这里(NSString *) TimeZone 参数是服务器时区

-(NSString *)convertTimeIntoLocal:(NSString *)defaultTime :(NSString *)TimeZone
{
NSDateFormatter *serverFormatter = [[NSDateFormatter alloc] init];
[serverFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:TimeZone]];
[serverFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *theDate = [serverFormatter dateFromString:defaultTime];
NSDateFormatter *userFormatter = [[NSDateFormatter alloc] init];
[userFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
[userFormatter setTimeZone:[NSTimeZone localTimeZone]];
NSString *dateConverted = [userFormatter stringFromDate:theDate];
return dateConverted;
}
小开

将 UTC 日期转换为本地日期

-(NSString *)getLocalDateTimeFromUTC:(NSString *)strDate
{
NSDateFormatter *dtFormat = [[NSDateFormatter alloc] init];
[dtFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
[dtFormat setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];
NSDate *aDate = [dtFormat dateFromString:strDate];


[dtFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
[dtFormat setTimeZone:[NSTimeZone systemTimeZone]];


return [dtFormat stringFromDate:aDate];
}

像这样使用

NSString *localDate = [self getLocalDateTimeFromUTC:@"yourUTCDate"];
小开

Swift 3 + : < em > UTC to Local and Local to UTC

extension Date {


// 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)
}


// 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)
}
}
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你可以试试这个:

NSDate *currentDate = [[NSDate alloc] init];
NSTimeZone *timeZone = [NSTimeZone defaultTimeZone];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterLongStyle];
[dateFormatter setTimeStyle:NSDateFormatterLongStyle];
[dateFormatter setTimeZone:timeZone];
[dateFormatter setDateFormat:@"ZZZ"];
NSString *localDateString = [dateFormatter stringFromDate:currentDate];
NSMutableString *mu = [NSMutableString stringWithString:localDateString];
[mu insertString:@":" atIndex:3];
NSString *strTimeZone = [NSString stringWithFormat:@"(GMT%@)%@",mu,timeZone.name];
NSLog(@"%@",strTimeZone);
小开

请用这个密码。

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


[dateFormatter setDateFormat:@"EEE, MMM d, yyyy - h:mm a"];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
NSString *timestamp = [dateFormatter stringFromDate:date];
小开

快速约会库解决方案:

// Take date by seconds in UTC time zone
var viewModelDate: Date = DateInRegion(seconds: Double(backendModel.scheduledTimestamp)).date


...


// Convert date to local timezone and convert to string by format rule.
label.text = viewModelDate.convertTo(region: .current).toFormat(" EEE MM/dd j:mm")

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