Type-safe font initiazer

FontUtils.swift

//
// MARK: Font utilities
//

enum FontFamily : String {
    case HelveticaNeue = "Helvetica Neue"
    case MontSerrat = "Montserrat"
}

enum FontWeight {
    case UltraLight,Thin,Light,Regular,Medium,Semibold,Bold,Heavy,Black
    
    var asFontWeightTraitValue:CGFloat {
        switch self {
        case .UltraLight: return UIFontWeightUltraLight
        case .Thin: return UIFontWeightThin
        case .Light: return UIFontWeightLight
        case .Regular: return UIFontWeightRegular
        case .Medium: return UIFontWeightMedium
        case .Semibold: return UIFontWeightSemibold
        case .Bold: return UIFontWeightBold
        case .Heavy: return UIFontWeightHeavy
        case .Black: return UIFontWeightBlack
        }
    }
}

func getFont(family:FontFamily,weight:FontWeight,size:CGFloat) -> UIFont? {
    let descriptor = UIFontDescriptor(fontAttributes:[
        UIFontDescriptorFamilyAttribute:family.rawValue,
        UIFontWeightTrait:weight.asFontWeightTraitValue
        ])
    return UIFont(descriptor: descriptor, size: size)
}

extension UIFont {
    convenience init(family:FontFamily,weight:FontWeight,size:CGFloat)
    {
        let descriptor = UIFontDescriptor(fontAttributes:[
            UIFontDescriptorFamilyAttribute:family.rawValue,
            UIFontWeightTrait:weight.asFontWeightTraitValue
            ])
        self.init(descriptor: descriptor, size: size)
    }
}

// helpers

extension UIFont {
  func scaled(scaleFactor:CGFloat) -> UIFont
  {
    let descriptor:UIFontDescriptor = self.fontDescriptor()
    let pointSize = descriptor.pointSize * scaleFactor
    let newFont = UIFont(descriptor:descriptor,size:pointSize)
    return newFont
  }
  
  func italicized() -> UIFont {
    let descriptor:UIFontDescriptor = self.fontDescriptor()
    let italicSymbolicTraits:UIFontDescriptorSymbolicTraits = .TraitItalic
    if let newDescriptor = descriptor.fontDescriptorWithSymbolicTraits(italicSymbolicTraits) {
      return UIFont(descriptor:newDescriptor,size:self.pointSize)
    }
    else {
      return self
    }
  }
}