确定 unicode 字符在 UI​​Font 中是否有字形

Question

我想知道某个 unicode 字符是否有字形表示，即使是级联字体。例如，假设我正在使用 UIFont.systemFont(withSize:18) 和一个字符串 \u{1CDA} 并且想知道这个字体是否会显示这个字符的图形表示，而不是默认的问号表示（即没有图形表示，甚至支持级联字体）。

Answer 1

这对我有用。 Swift3、XCode8.6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))")