How does one subtract hours from an NSDate?

Question

I would like to subtract 4 hours from a date. I read the date string into an NSDate object use the following code:

NSDateFormatter * dateFormatter = [[[NSDat         


        

Answer 1

NSCalendar is the general API for changing dates based on human time units. For this, you can use NSCalendar's -dateByAddingComponents:toDate:options: with a negative number of hours.