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

Since iOS 8 there is the more convenient dateByAddingUnit:

Swift 2.x

//subtract 3 hours
let calendar = NSCalendar.autoupdatingCurrentCalendar()
newDate = calendar.dateByAddingUnit(.Hour, value: -3, toDate: originalDate, options: [])