NSDateFormatter can't parse '1988-04-10' to NSDate instance in iOS 6 . Is it a bug?
cocoa-touch, ios, nscalendar, nsdate, objective-c
Solution
Sunday, April 10th, 00:00 was the switch for Daylight Saving Time in Shanghai that year.
According to the great WWDC 2011 Video: Performing Calendar Calculations this can lead to undefined behavior. In the video Rio de Janeiro is chosen as example for the very same reason.
One workaround could be to add a time, that is save, as 3pm. Another to do the calculation on NSDateComponents. Both workarounds are explained in the video.
Problem
I encountered a stranger question. NSDateFormatter can't parse `1988-04-10` to NSDate instance in iOS 6. But it works in iOS 4 and iOS 5. Is it a bug? Following is the code. It is very simple. ``` NSArray *values = @[@"1988-04-09", @"1988-04-10", @"1988-04-11"]; NSDateFormatter* df = [[NSDateFormatter alloc] init]; NSLocale *posixLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]; [df setLocale:posixLocale]; [df setDateFormat:@"yyyy'-'MM'-'dd"]; NSLog(@"timeZone:%@, locale:%@", df.timeZone, df.locale.localeIdentifier); NSDate* date = nil; for (NSString *value in values) { date = [df dateFromString:value]; NSLog(@"The date is %@", date); } [posixLocale release]; [df release]; ``` Following is the result in iOS 4 and iOS 5. ``` 2013-03-19 09:55:32.249 SampleProject[1844:f803] timeZone:Asia/Shanghai (CST (China)) offset 28800, locale:en_US_POSIX 2013-03-19 09:55:32.250 SampleProject[1844:f803] The date is 1988-04-08 16:00:00 +0000 2013-03-19 09:55:32.250 SampleProject[1844:f803] The date is 1988-04-09 16:00:00 +0000 2013-03-19 09:55:32.251 SampleProject[1844:f803] The date is 1988-04-10 15:00:00 +0000 ``` Following is the result in iOS 6. ``` 2013-03-19 09:42:40.824 SampleProject[1455:11303] timeZone:Asia/Shanghai (GMT+08:00) offset 28800, locale:en_US_POSIX 2013-03-19 09:42:40.827 SampleProject[1455:11303] The date is 1988-04-08 16:00:00 +0000 2013-03-19 09:42:40.827 SampleProject[1455:11303] The date is (null) 2013-03-19 09:42:40.828 SampleProject[1455:11303] The date is 1988-04-10 15:00:00 +0000 ``` It is null for `1988-04-10`. Is is a bug. Can anyone explain it?