獲取字符寬度：並非自適應。coretext去計算

<SPAN style="FONT-SIZE: 24px">獲取字符寬度：並非自適應。coretext去計算
UniChar ch = [ns_str characterAtIndex:0];
    CGGlyph glyph = 0;
    CTFontGetGlyphsForCharacters(fontRef, &ch, &glyph, 1);
    CGSize glyphSize;
    CTFontGetAdvancesForGlyphs(fontRef, kCTFontHorizontalOrientation, &glyph, &glyphSize, 1);
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