题
我如何获得GMT时间?
NSDate *c =[NSDate date];
为系统时间,而不是GMT。
解决方案
- (NSDate*) convertToUTC:(NSDate*)sourceDate
{
NSTimeZone* currentTimeZone = [NSTimeZone localTimeZone];
NSTimeZone* utcTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];
NSInteger currentGMTOffset = [currentTimeZone secondsFromGMTForDate:sourceDate];
NSInteger gmtOffset = [utcTimeZone secondsFromGMTForDate:sourceDate];
NSTimeInterval gmtInterval = gmtOffset - currentGMTOffset;
NSDate* destinationDate = [[[NSDate alloc] initWithTimeInterval:gmtInterval sinceDate:sourceDate] autorelease];
return destinationDate;
}
其他提示
这是拉敏的回答的一个简化版本
+ (NSDate *) GMTNow
{
NSDate *sourceDate = [NSDate date];
NSTimeZone* currentTimeZone = [NSTimeZone localTimeZone];
NSInteger currentGMTOffset = [currentTimeZone secondsFromGMT];
[sourceDate addTimeInterval:currentGMTOffset];
return sourceDate;
}
如果这是为了显示你想要显示它,使用NSDateFormatter像这样:
NSDate *myDate = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];
// Set date style:
[dateFormatter setDateStyle:NSDateFormatterShortStyle];
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];
NSString *GMTDateString = [dateFormatter stringFromDate: myDate];
如果执行日期计算,这些类别可以是有用的。已经转换你的日期是“规范化”(即,具有相同的月,日和年,但在+ 1200 UTC),如果再使用NSCalendar,它也设定为UTC(+[NSCalendar normalizedCalendar]
),这是进行后续计算LL所有锻炼。
@implementation NSDate (NormalizedAdditions)
+ (NSDate *)normalizedDateFromDateInCurrentCalendar:(NSDate *)inDate
{
NSDateComponents *todayComponents = [[NSCalendar currentCalendar] components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
fromDate:inDate];
[todayComponents setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];
[todayComponents setHour:12];
return [[NSCalendar normalizedCalendar] dateFromComponents:todayComponents];
}
+ (NSDate *)normalizedDate
{
return [self normalizedDateFromDateInCurrentCalendar:[NSDate date]];
}
@end
@implementation NSCalendar (NormalizedAdditions)
+ (NSCalendar *)normalizedCalendar
{
static NSCalendar *gregorian = nil;
if (!gregorian) {
gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];
}
return gregorian;
}
@end
+ (NSDate*) convertToGMT:(NSDate*)sourceDate
{
NSTimeZone* currentTimeZone = [NSTimeZone localTimeZone];
NSTimeInterval gmtInterval = [currentTimeZone secondsFromGMTForDate:sourceDate];
NSDate* destinationDate = [[[NSDate alloc] initWithTimeInterval:gmtInterval sinceDate:sourceDate] autorelease];
return destinationDate;
}
NSDate的内部存储时区 - 有你可以打电话和传中的目标时区,如果你仅仅指刚想要的日期的字符串表示的一些功能,看到的苹果的文档
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