NSDate loses and hour when adding a month during DST change? - ios

Question

When trying to add a month using the suggested 'correct' method on all the stackoverflow questions I can find, the date I get back always loses an hour due to DST.
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *component = [[NSDateComponents alloc] init];
[component setDay:29];
[component setMonth:3];
[component setYear:2015];
NSDate *date = [gregorian dateFromComponents:component];
NSLog(#"Date: %#", date);
NSDateComponents *monthComponent = [[NSDateComponents alloc] init];
monthComponent.month = 1;
NSDate *newDate = [gregorian dateByAddingComponents:monthComponent toDate:date options:0];
NSLog(#"newDate: %#", newDate);
The output of this code is:
Date: 2015-03-29 00:00:00 +0000
newDate: 2015-04-28 23:00:00 +0000
How can I add a month across a DST change and keep the time at midnight?
Thanks for any help.
Example in response to gnasher729 below:
In the example the first two dates would be set at midnight and the second two would be 23:00. What would be the best practice to implement something like this while keeping all the outputted dates to the desired midnight time?
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *initialDateComponent = [[NSDateComponents alloc] init];
[initialDateComponent setDay:29];
[initialDateComponent setMonth:1];
[initialDateComponent setYear:2015];
NSDate *date = [gregorian initialDateComponent];
NSLog(#"Date: %#", date);
NSDateComponents *monthComponent = [[NSDateComponents alloc] init];
monthComponent.month = 1;
monthComponent.hour = 0;
NSMutableArray *eventAlarmDate = [[NSMutableArray alloc] init];
int numberOfRepeatingMonths = 4;
for(int x = 0; 0 < numberOfRepeatingMonths; x++) {
date = [gregorian dateByAddingComponents:monthComponent toDate:date options:0];
[eventAlarmDate addObject:date];
}

Answer 1

You are actually asking us how to introduce a bug in your code.
The result is correct. Adding one month during a DST change will and must add one hour more or one hour less than full days.
NSDate always displays its date in UTC, which is British time without DST correction. The date calculated is with DST corrections, and it depends on your location. If you are in India, midnight is at 5:30 am UTC (or 18:30 pm UTC on the previous day, not sure).