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)
Swift 4
label.font = UIFont.systemFont(ofSize: 22, weight: UIFont.Weight.bold)