确定 Unicode 字符在 UIFont 中是否有字形

Question

我想找出某个 unicode 字符是否具有字形表示，即使使用级联字体也是如此。 例如，假设我正在使用UIFont.systemFont(withSize:18)和字符串u{1CDA}，并且想知道此字体是否将显示此字符的图形表示形式，而不是默认的问号表示形式(即没有图形表示形式，即使通过支持的级联字体也是如此)。

Answer 1

这对我有用。 Swift 3，XCode 8.6版本：

import UIKit
import CoreText
extension Font {
public func hasGlyph(utf32 character:UInt32) -> Bool {
var code_point: [UniChar] = [
UniChar.init(truncatingBitPattern: character),
UniChar.init(truncatingBitPattern: character >> 16)
]
var glyphs: [CGGlyph] = [0,0]
let result = CTFontGetGlyphsForCharacters(self as CTFont, &code_point, &glyphs, glyphs.count)
return result
}
}
public class Glypher {
let font:UIFont
var support:[CTFont] = []
public init(for font:UIFont, languages:[String] = ["en"]) {
self.font = font
let languages = languages as CFArray
let result = CTFontCopyDefaultCascadeListForLanguages(font as CTFont, languages)
let array = result as! Array<CTFontDescriptor>
for descriptor in array {
support.append(CTFontCreateWithFontDescriptor(descriptor,18,nil))
}
}
public func isGlyph(_ point:UInt32) -> Bool {
return font.hasGlyph(utf32:point) || isGlyphSupported(point)
}
public func isGlyphSupported(_ point:UInt32) -> Bool {
for font in support {
var code_point: [UniChar] = [
UniChar.init(truncatingBitPattern: point),
UniChar.init(truncatingBitPattern: point >> 16)
]
var glyphs: [CGGlyph] = [0, 0]
let result = CTFontGetGlyphsForCharacters(font as CTFont, &code_point, &glyphs, glyphs.count)
if result {
return true
}
}
return false
}
}
let glypher = Glypher(for:UIFont.systemFont(ofSize:18))
if glypher.isGlyph(0x1CDA) {
print("bingo!")
}

Answer 2

这可能也有效，它不检查字形，但它检查字符集

import CoreText
func isSupported(unicode: UnicodeScalar, font: UIFont) -> Bool {
let coreFont: CTFont = font
let characterSet: CharacterSet = CTFontCopyCharacterSet(coreFont) as CharacterSet
return characterSet.contains(unicode)
}

示例测试：

let testString = "R"
let font = UIFont.boldSystemFont(ofSize: 10.0)
print("(isSupported(unicode: testString.unicodeScalars.first!, font: font))")

Answer 3

这在很大程度上是基于@andrewz的答案，所以大部分功劳都归功于他们！我发现某些表情符号给出假阴性(包括)存在一些问题，所以我进行了一些修改，包括✋将表情符号作为String传递：

(注意：我有Font而不是UIFont，因为我在iOS和macOS上都使用它，所以有一个typealias可以在两个字体类之间切换，你可以用NS或UI作为前缀，适合你选择的平台！

extension Font {

func canRender(emoji: String) -> Bool {
var code_points = Array(emoji.utf16)
var glyphs: [CGGlyph] = Array(repeating: 0, count: code_points.count)
return CTFontGetGlyphsForCharacters(self as CTFont, &code_points, &glyphs, glyphs.count)
}

}
class Glypher {
private let font: Font
private var support: [CTFont] = []
init(for font: Font, languages: [String] = ["en"]) {
self.font = font
let languages = languages as CFArray
let result = CTFontCopyDefaultCascadeListForLanguages(font as CTFont, languages)
let array = result as! Array<CTFontDescriptor>
for descriptor in array {
support.append(CTFontCreateWithFontDescriptor(descriptor, 18, nil))
}
}
func isRenderable(emoji: String) -> Bool {
return font.canRender(emoji: emoji) || renderSupported(emoji: emoji)
}
func renderSupported(emoji: String) -> Bool {
var code_points = Array(emoji.utf16)
var glyphs: [CGGlyph] = Array(repeating: 0, count: code_points.count)
for font in support where CTFontGetGlyphsForCharacters(font as CTFont, &code_points, &glyphs, glyphs.count) {
return true
}
return false
}

}