如何找到 UIFontFeatureTypeIdentifierKey 的不同键？

Question

我正在使用 New Font Features at WWDC 2015:

中的这个很棒的代码

import UIKit

let pointSize : CGFloat = 60.0
let systemFontDesc = UIFont.systemFont(ofSize: pointSize,
                                             weight: UIFontWeightLight).fontDescriptor
let fractionFontDesc = systemFontDesc.addingAttributes(
    [
        UIFontDescriptorFeatureSettingsAttribute: [
            [
                UIFontFeatureTypeIdentifierKey: kFractionsType,
                UIFontFeatureSelectorIdentifierKey: kDiagonalFractionsSelector,
                ],
        ]
    ] )

let label = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 100))

label.font = UIFont(descriptor: fractionFontDesc, size:pointSize)
label.text = "12/48"

WWDC 视频展示了 UIFontDescriptorFeatureSettingsAttribute 的其他用途，例如 superiors (e = mc²)

但是解锁其他属性的钥匙是什么？

UIFontDescriptorFeatureSettingsAttribute 的文档页面只是说它是一个包含 UIFontFeatureTypeIdentifierKey 和 UIFontFeatureSelectorIdentifierKey 的字典数组。

这两个键的文档 (type and selector) 只是说它们是 NSNumber。

对于分数，类型是 kFractionsType，选择器是 kDiagonalFractionsSelector

如何找到其他可用功能的密钥？

Answer 1

Core Text 将为您列出字体的隐藏功能：

let desc = UIFontDescriptor(name: "Didot", size: 20) as CTFontDescriptor
let f = CTFontCreateWithFontDescriptor(desc,0,nil)
let arr = CTFontCopyFeatures(f)
print(arr as Any)

对于具有神奇名称的功能，您必须查看 SFNTLayoutTypes.h header.

如何找到 UIFontFeatureTypeIdentifierKey 的不同键？

How to find the different keys for UIFontFeatureTypeIdentifierKey?

uifont

ios

swift