Get the variation of the UIFont

UIFont * GetVariationOfFontWithTrait(UIFont *baseFont, CTFontSymbolicTraits trait)

UIFont * GetVariationOfFontWithTrait(UIFont *baseFont, CTFontSymbolicTraits trait) {
    CGFloat fontSize = [baseFont pointSize];
    CFStringRef baseFontName = (__bridge CFStringRef)[baseFont fontName];
    CTFontRef baseCTFont = CTFontCreateWithName(baseFontName, fontSize, NULL);
    CTFontRef ctFont = CTFontCreateCopyWithSymbolicTraits(baseCTFont, 0, NULL, trait, trait);
    NSString *variantFontName = CFBridgingRelease(CTFontCopyName(ctFont, kCTFontPostScriptNameKey));
    UIFont *variantFont = [UIFont fontWithName:variantFontName size:fontSize];
    CFRelease(ctFont);
    CFRelease(baseCTFont);
    return variationFont;
}