Rails-style date/time arithmetics in Swift

Admit it, you've always been jealous of you friend the Rails developer being able to write nice, readable date operations like these:

some_future_date = 4.months.from_now
the_past = (2.days + 3.years).ago

Well, with Swift you can now have those in your iOS app as well! We can simply extent the Int data type with some computed properties to convert the values into NSDateComponents. Then let's also add operator functions for addition and subtraction working with two NSDateComponents and we can write lines like these, too:

println("now:                   \(NSDate.date())")
println("8 days later:          \(8.days.fromNow)")
println("2 weeks before:        \(2.weeks.ago)")
println("5 days, 3 month later: \((5.days + 3.months).fromNow)")