Open Radar

 
Summary:
It is stated in the documentation that NSISO8601DateFormatter with the NSISO8601DateFormatWithInternetDateTime will parse dates formatted according to RFC 3339. However, this is not the case as it fails to parse strings with non-integer dates, which is part of RFC 3339.

Steps to Reproduce:
Run the code below on a Mac with 10.12.1 or a device with iOS 10, which tries to parse a date string that is used as an example in RFC 3339 on page 9.

NSISO8601DateFormatter *formatter = [[NSISO8601DateFormatter alloc] init];
formatter.formatOptions = NSISO8601DateFormatWithInternetDateTime;
NSLog(@"%@", [formatter dateFromString:@"1985-04-12T23:20:50.52Z"]);

Expected Results:
As RFC 3339 page 9 states, this should be parsed as 20 minutes and 50.52 seconds after the 23rd hour of April 12th, 1985 in UTC.

Actual Results:
dateFromString: returns nil.

Version:
iOS 10.1.1, Mac 10.12.1

Notes:
RFC 3339:

https://www.ietf.org/rfc/rfc3339

NSISO8601DateFormatWithInternetDateTime documentation:

https://developer.apple.com/reference/foundation/nsiso8601dateformatoptions/nsiso8601dateformatwithinternetdatetime?language=objc

Related bug report:

http://www.openradar.me/28425750

Configuration:
iOS Simulator and MacBook Air