We're currently looking into moving our app to iOS 11 when we discovered a portion of our legacy code used to convert UTC date times to localized date time strings is returning differing values between iOS 10 and iOS 11. When running a fresh install of our app on simulators (after resetting content and settings) we see the following output:
10.3.1:
(lldb) po [NSTimeZone localTimeZone]
Local Time Zone (America/Toronto (EDT) offset -14400 (Daylight))
11.0:
(lldb) po [NSTimeZone localTimeZone]
Local Time Zone (America/Los_Angeles (PDT) offset -25200 (Daylight))
I created a fresh project and have the same results when I run the following snippit highlighting the issue:
- (void)logLocalizedDate {
// Setup: Create a UTC date time
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss zzz"];
NSDate *utcDate = [dateFormatter dateFromString: @"2017-08-18 00:00:00 UTC"];
[NSTimeZone setDefaultTimeZone:[NSTimeZone timeZoneWithName:@"UTC"]];
// Now convert it to a local time zone string
NSString *localizedDateString = [self computeLocalTimeZoneDayStringFromDate:utcDate];
NSLog(@"Computed Date String: %@", localizedDateString);
}
-(NSString *)computeLocalTimeZoneDayStringFromDate:(NSDate *)dateToCompute
{
// Create a localized date formatter
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en"]];
[dateFormatter setDateFormat:@"yyyy-MM-dd"];
// This call differs between iOS10 and iOS 11
dateFormatter.timeZone = [NSTimeZone localTimeZone];
NSString *date = [dateFormatter stringFromDate:dateToCompute];
return date;
}Anything wrong here? We've never had an issue in the past and similar code in our app has been ported from iOS 8 -> 9 -> 10 with no issues. In fact it hasn't changed since 2014.
Thanks
