Find DST (Daylight Savings Time) timestamp using Objective-C/C?
c, cocoa-touch, dst, ios, objective-c
Solution
Yes, there is - you can use `[NSTimeZone nextDaylightSavingTimeTransitionAfterDate:]` method. This returns an `NSDate`, which you can use with `daylightSavingTimeOffsetForDate` to establish what the offset is.
Normally you'd use this to find the next offset, but you can obviously run it more than once with different dates to get a series of upcoming daylight saving changes. There is also a convenience method `nextDaylightSavingTimeTransition` which will always return the next transition.
Problem
Is there a way to get the specific date (way) when daylight davings begins and ends for each country using C or Objective-C? In the Mexico, summer time begins on the first Sunday in April at 2:00am, and ends on the last Sunday in October at 2:00am. In many POSIX systems this is written as ``` M4.1.0/2,M10.5.0/2 (Begins: Month 4, 1st Sunday at 02:00AM, Ends: Month 10, last Sunday at 02:00AM) ``` I know it is possible to know if daylight savings is currently active using ``` NSTimeZone* systemTimeZone = [NSTimeZone systemTimeZone]; BOOL dstIsOn = [systemTimeZone isDaylightSavingTime]; ``` and that it is possible to get the time until the next `Daylight Savings` begins ``` NSTimeZone* systemTimeZone = [NSTimeZone systemTimeZone]; NSTimeInterval delta = [systemTimeZone daylightSavingTimeOffset]; ``` BUT: How would I go about finding the specific day that the daylight savings begins/ends? Is there some killer table out there that I have not been able to find? Any help would be greatly appreciated!