You can declare a UIFont as follows:

var font: UIFont!

UIFont has more init() methods:

• UIFont.init(descriptor: UIFontDescriptor, size: CGFloat)
• UIFont.init(name: String, size: CGFloat)

Therefore, you can initialize a UIFont like this:

let font = UIFont(name: "Helvetica Neue", size: 15)

The default font is System, size 17.

To change a label's text font, you need to access its font property:

label.font = UIFont(name:"Helvetica Neue", size: 15)

The code above will change the font of the label to Helvetica Neue, size 15. Beware that you must spell the font name correctly, otherwise it will throw this error, because the initialized value above is an Optional, and thus can be nil:

Unexpectedly found nil while unwrapping an Optional value