如何在swift中使系统字体“黑色斜体”？

Question

我正在尝试添加粗细为“Heavy”（不是粗体）的系统字体，并尝试将其设置为斜体。我看到了其他 stackoverflow 解决方案，但它似乎不起作用。这是我所做的：

let percentageLabel: UILabel = {
       let label = UILabel()
        label.text = "0"
        label.textAlignment = .center
        label.textColor = .white
        label.font = UIFont.systemFont(ofSize: 32, weight: .heavy, traits: .traitItalic)
       return label
    }()

堆栈溢出帖子中建议的扩展

extension UIFont {

    static func systemFont(ofSize: CGFloat, weight: UIFont.Weight, traits: UIFontDescriptor.SymbolicTraits) -> UIFont? {
         let font = UIFont.systemFont(ofSize: ofSize, weight: weight)

         if let descriptor = font.fontDescriptor.withSymbolicTraits(traits) {
             return UIFont(descriptor: descriptor, size: ofSize)
         }

         return nil
     }
}

问题是，当我尝试所有建议的解决方案时，粗体和斜体似乎有效，但黑色和斜体不起作用。它仍然呈现为常规斜体。

Answer 1

斯威夫特 5. *

extension UIFont {
      
    class func italicSystemFont(ofSize size: CGFloat, weight: UIFont.Weight = .regular)-> UIFont {
        let font = UIFont.systemFont(ofSize: size, weight: weight)
        switch weight {
        case .ultraLight, .light, .thin, .regular:
            return font.withTraits(.traitItalic, ofSize: size)
        case .medium, .semibold, .bold, .heavy, .black:
            return font.withTraits(.traitBold, .traitItalic, ofSize: size)
        default:
            return UIFont.italicSystemFont(ofSize: size)
        }
     }
    
     func withTraits(_ traits: UIFontDescriptor.SymbolicTraits..., ofSize size: CGFloat) -> UIFont {
        let descriptor = self.fontDescriptor
            .withSymbolicTraits(UIFontDescriptor.SymbolicTraits(traits))
        return UIFont(descriptor: descriptor!, size: size)
     }
      
}

用法：

myLabel.font = UIFont.italicSystemFont(ofSize: 34, weight: .black)

Answer 2

尝试这个

     label.font = UIFont.systemFont(ofSize: 32, weight: .black, traits: .traitItalic)
//If you just want Italic then use this
   labelInfo.font = UIFont.italicSystemFont(ofSize: 32)