Set Specific Font Weight for UILabel in Swift - ios

Question

When people have asked how to set a bold font, most people suggest:
let boldFont = UIFont.boldSystemFont(ofSize: ___)
But take a look at all the font weights that the standard system font offers:
So my question is how do you set a light, semibold, or heavy font weight? The only way that I know how is:
sectionLabel.font = [UIFont fontWithName:#"TrebuchetMS-Bold" size:18];
However, I'm still asking because this isn't strongly typed. Most other class attributes are set by selecting from a fixed set of options and don't require passing a string that I could mistype. I guess I could set my own global enum... But any better ideas?

Answer 1

I couldn't get the UIFontDescriptor to work with the font weight trait but there is another approach.
let font = UIFont.systemFont(ofSize: 20, weight: .light)
Replace .light with whichever value you want from UIFont.Weight which basically matches the dropdown list shown in your question.

Answer 2

You can use this extension. It assigns the weight to the fontDescriptor's weight key and instantiate your font with this new descriptor.
extension UIFont {
func withWeight(_ weight: UIFont.Weight) -> UIFont {
let newDescriptor = fontDescriptor.addingAttributes([.traits: [
UIFontDescriptor.TraitKey.weight: weight]
])
return UIFont(descriptor: newDescriptor, size: pointSize)
}
}

Answer 3

The very old thread, but someone may be interested in how to do it in Swift.
UIFont.Weight defines all of the options:
ultraLight
thin
light
regular
medium
semibold
bold
heavy
black
you can use simply like that, e.g.:
label.font = UIFont.systemFont(ofSize: size, weight: .bold)
or if you want to keep the previous size:
label.font = UIFont.systemFont(ofSize: label.font!.pointSize, weight: .bold)

Answer 4

Even more:
let font = UIFont.systemFont(ofSize: 20, weight: UIFont.Weight(500))

Answer 5

If you want to use system fonts, for Swift 5 a simple extension would look like this:
extension UIFont {
func withWeight(_ weight: UIFont.Weight) -> UIFont {
UIFont.systemFont(ofSize: pointSize, weight: weight)
}
}