我正在使用Parse.com存储一些值:
这些是GMT值。如何将这些转换为设备的当前时区并获得NSDate?
答案 0 :(得分:54)
NSDate始终以GMT表示。这就是你如何代表它可能会改变的。
如果您要将日期打印到label.text
,请使用NSDateFormatter
和[NSTimeZone localTimeZone]
将其转换为字符串,如下所示:
NSString *gmtDateString = @"08/12/2013 21:01";
NSDateFormatter *df = [NSDateFormatter new];
[df setDateFormat:@"dd/MM/yyyy HH:mm"];
//Create the date assuming the given string is in GMT
df.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];
NSDate *date = [df dateFromString:gmtDateString];
//Create a date string in the local timezone
df.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:[NSTimeZone localTimeZone].secondsFromGMT];
NSString *localDateString = [df stringFromDate:date];
NSLog(@"date = %@", localDateString);
// My local timezone is: Europe/London (GMT+01:00) offset 3600 (Daylight)
// prints out: date = 08/12/2013 22:01
答案 1 :(得分:25)
我发现的最简单方法是:
NSDate *someDateInUTC = …;
NSTimeInterval timeZoneSeconds = [[NSTimeZone localTimeZone] secondsFromGMT];
NSDate *dateInLocalTimezone = [someDateInUTC dateByAddingTimeInterval:timeZoneSeconds];
答案 2 :(得分:5)
这是将NSDate更改为本地时区日期的非常简洁的方法
extension NSDate {
func toLocalTime() -> NSDate {
let timeZone = NSTimeZone.local
let seconds : TimeInterval = Double(timeZone.secondsFromGMT(for:self as Date))
let localDate = NSDate(timeInterval: seconds, since: self as Date)
return localDate
}
}
取自https://agilewarrior.wordpress.com/2012/06/27/how-to-convert-nsdate-to-different-time-zones/
答案 3 :(得分:3)
创建如下的Xcode测试用例可以帮助我们记住规则"永远":
- (void)test2015_05_23_07_07_07_Toronto {
NSString *utcDateString = @"2015_05_23 12:07:07";
NSDateFormatter *dateFormatter = [NSDateFormatter new];
dateFormatter.dateFormat = @"yyyy_MM_dd HH:mm:ss";
dateFormatter.timeZone = [NSTimeZone timeZoneWithName:@"UTC"];
NSDate *date2015_05_23_12_07_07_UTC = [dateFormatter dateFromString:utcDateString];
XCTAssertTrue([date2015_05_23_12_07_07_UTC.description isEqualToString:@"2015-05-23 12:07:07 +0000"]);
dateFormatter.timeZone = [NSTimeZone timeZoneWithName:@"EST"];
NSString *torontoDateString = [dateFormatter stringFromDate:date2015_05_23_12_07_07_UTC];
XCTAssertTrue([torontoDateString isEqualToString:@"2015_05_23 07:07:07"]);
// change format to add ZZZ
dateFormatter.dateFormat = @"yyyy_MM_dd HH:mm:ss ZZZ";
torontoDateString = [dateFormatter stringFromDate:date2015_05_23_12_07_07_UTC];
XCTAssertTrue([torontoDateString isEqualToString:@"2015_05_23 07:07:07 -0500"]);
XCTAssertEqual(1432382827, [date2015_05_23_12_07_07_UTC timeIntervalSince1970]);
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
calendar.timeZone = [NSTimeZone timeZoneWithName:@"EST"];
NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond) fromDate:date2015_05_23_12_07_07_UTC];
XCTAssertEqual(2015, components.year);
XCTAssertEqual(5, components.month);
XCTAssertEqual(23, components.day);
XCTAssertEqual(7, components.hour);
XCTAssertEqual(7, components.minute);
XCTAssertEqual(7, components.second);
}
答案 4 :(得分:2)
您可以使用NSDateFormatter来实现此结果。
NSString *dateAsString = @"08/07/2013 04:06";
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"dd/MM/yyyy HH:mm"];
NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[df setTimeZone:gmt];
NSDate *myDate = [df dateFromString: dateAsString];
NSLog(@"date: %@", myDate);
答案 5 :(得分:1)
这个问题有很多答案,但我会推荐这个:
Convert GMT NSDate to device's current Time Zone
NSString *dateStr = @"2012-07-16 07:33:01";
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *date = [dateFormatter1 dateFromString:dateStr];
NSLog(@"date : %@",date);
NSTimeZone *currentTimeZone = [NSTimeZone localTimeZone]; // <- Local time zone
NSTimeZone *utcTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];
NSInteger currentGMTOffset = [currentTimeZone secondsFromGMTForDate:date1];
NSInteger gmtOffset = [utcTimeZone secondsFromGMTForDate:date1];
NSTimeInterval gmtInterval = currentGMTOffset - gmtOffset;
NSDate *destinationDate = [[[NSDate alloc] initWithTimeInterval:gmtInterval sinceDate:date1] autorelease];
NSDateFormatter *dateFormatters = [[NSDateFormatter alloc] init];
[dateFormatters setDateFormat:@"dd-MMM-yyyy hh:mm"];
[dateFormatters setDateStyle:NSDateFormatterShortStyle];
[dateFormatters setTimeStyle:NSDateFormatterShortStyle];
[dateFormatters setDoesRelativeDateFormatting:YES];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];
dateStr = [dateFormatters stringFromDate: destinationDate];
NSLog(@"DateString : %@", dateStr);