How to use new San Francisco font in iOS 9?

In iOS 9 it is the system font, so you could do:

let font = UIFont.systemFontOfSize(18)

You can use the font name directly, but I don’t think this is safe:

let font = UIFont(name: ".SFUIText-Medium", size: 18)!

You can also create the font with specific weight, like so:

let font = UIFont.systemFontOfSize(18, weight: UIFontWeightMedium)

or

let font = UIFont.systemFontOfSize(18, weight: UIFontWeightLight)