如何获得符合可访问性设置的单空格字体

这是对的扩展 UIFontDescriptor 它返回给定文本样式的首选等距字体描述符。没有简单的方法可以使用 UIFont 或 UIFontDescriptor . 这种解决方案试图找到一种好的等距字体,如果需要,可以求助于Courier。

extension UIFontDescriptor {
    static let monoDescriptor: UIFontDescriptor = {
        // Attempt to find a good monospaced, non-bold, non-italic font
        for family in UIFont.familyNames {
            for name in UIFont.fontNames(forFamilyName: family) {
                let f = UIFont(name: name, size: 12)!
                let fd = f.fontDescriptor
                let st = fd.symbolicTraits
                if st.contains(.traitMonoSpace) && !st.contains(.traitBold) && !st.contains(.traitItalic) && !st.contains(.traitExpanded) && !st.contains(.traitCondensed) {
                    return fd
                }
            }
        }

        return UIFontDescriptor(name: "Courier", size: 0) // fallback
    }()

    class func preferredMonoFontDescriptor(withTextStyle style: UIFontTextStyle) -> UIFontDescriptor {
        // Use the following line if you need a fully monospaced font
        let monoDescriptor = UIFontDescriptor.monoDescriptor

        // Use the following two lines if you only need monospaced digits in the font
        //let monoDigitFont = UIFont.monospacedDigitSystemFont(ofSize: 0, weight: .regular)
        //let monoDescriptor = monoDigitFont.fontDescriptor

        // Get the non-monospaced preferred font
        let defaultFontDescriptor = preferredFontDescriptor(withTextStyle: style)
        // Remove any attributes that specify a font family or name and remove the usage
        // This will leave other attributes such as size and weight, etc.
        var fontAttrs = defaultFontDescriptor.fontAttributes
        fontAttrs.removeValue(forKey: .family)
        fontAttrs.removeValue(forKey: .name)
        fontAttrs.removeValue(forKey: .init(rawValue: "NSCTFontUIUsageAttribute"))
        let monospacedFontDescriptor = monoDescriptor.addingAttributes(fontAttrs)

        return monospacedFontDescriptor.withSymbolicTraits(defaultFontDescriptor.symbolicTraits) ?? monospacedFontDescriptor
    }
}

请注意有关是否需要完全等距的字体或只有等距数字的字体的注释。注释/取消注释这些行以满足您的特定需要。

示例用法:

let bodyMonospacedFont = UIFont(descriptor: .preferredMonoFontDescriptor(withTextStyle: .body), size: 0)
textview.font = bodyMonospacedFont

以下是一些测试代码,以确认 preferredMonoFontDescriptor(withTextStyle:) 适用于所有样式:

let textStyles: [UIFontTextStyle] = [ .body, .callout, .caption1, .caption2, .footnote, .headline, .subheadline, .largeTitle, .title1, .title2, .title3 ]
for style in textStyles {
    let nfont = UIFont(descriptor: .preferredFontDescriptor(withTextStyle: style), size: 0)
    let mfont = UIFont(descriptor: .preferredMonoFontDescriptor(withTextStyle: style), size: 0)
    print(style)
    print(nfont)
    print(mfont)
}

如果比较每对结果,它们的大小、重量和样式都相同,只是字体不同。