Created: 2012-03-23 20:46
Updated: 2019-01-16 09:53
License: bsd-2-clause

NSFormatter for ISO 8601

A Cocoa NSFormatter subclass for converting ISO 8601 formatted string to NSDate, and vice versa.

The parser is implemented using re2c. Thanks to re2c, it is much faster than NSDateFormatter is.

Supported Formats

  • Calendar Date
  • Ordinal Date
  • Week Date
  • Local Time with Decimal Fractions
  • Midnight
  • Time Zone

Unsupported Formats

  • BC Date
  • Basic Format of Ordinal Date Expanded Representation (Year > 9999)
  • Local Time with Leap Second (Second >= 60.0)
  • Time Inverval
  • Duration
  • Recurring Time Interval


To convert ISO 8601 string to NSDate. You can use NJISO8601DateFromString() function without any configuration.

NSDate *date = NJISO8601DateFromString(@"2011-02-27T11:03:06+09:00");

or, you can use the NJISO8601Formatter the same way as you do with NSDateFormatter.

NJISO8601Formatter *formatter = [[NJISO8601Formatter alloc] init];

NSDate *date = [formatter dateFromString:@"2011-02-07T11:03:06+09:00"];

To convert NSDate to ISO 8601 formatted string.

NJISO8601Formatter *formatter = [[NJISO8601Formatter alloc] init];

NSString *string = [formatter stringFromDate:date];

Also, you can customize output format like this:

[formatter setDateStyle:NJISO8601FormatterDateStyleWeekExtended];
[formatter setTimeZoneStyle:NJISO8601FormatterTimeZoneStyleExtended];
[formatter setFractionSeparator:NJISO8601FormatterFractionSeparatorDot];
[formatter setFractionDigits:6];
[formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:(8 * 60 * 60)]];
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