I get seconds value from my function. For example I got: 22'356 seconds. Now I want to **subtract** this value from **now** and get `NSDate`, How can I achieve it?

Also, I have a function:

```
let date = NSDate(timeIntervalSinceNow:time.doubleValue)
let dateFormatter = NSDateFormatter()

dateFormatter.dateFormat = "dd.MM.yyyy"
self.lastSeenText = "last seen on \(dateFormatter.stringFromDate(date))"

```

but this function **adds** difference to **now**. For example, if difference is 2 days, and today is 12.10.15, it will print 14.10.15.

How can I get opposite value, 10.10.15?