weight
The numerical value that corresponds to a font face.
Declaration
static let weight: UIFontDescriptor.TraitKeyDiscussion
The value of this key is an NSNumber object. The valid value range is from -1.0 to 1.0, where 0.0 corresponds to the regular weight constant. The negative side of the value range indicates that the font is light or thin; the positive side means the font is heavier or bolder. For example, the font face ultraLight has the approximate value of -0.8, and black has the approximate value of 0.62. When providing a weight that doesn’t precisely match a font face in the family, the system locates an available face that represents the closest match.
You can use a font face constant to specify a weight; for a list of constants, see UIFont.Weight.
To access the weight of a font, first retrieve the font’s traits dictionary information:
let font = UIFont.systemFont(ofSize: 21, weight: .bold)
if let traits = font.fontDescriptor.object(forKey: .traits) as? [UIFontDescriptor.TraitKey: Any]{
let weightValue = traits[.weight]
}