How to make a UIFont bold or italic?

Question

Having a UILabel with any font, how can I find out if it is already bold? Or how can I make it bold? In CSS, I have a font-weight attribute. I would like to have something similar.

Everything I found out so far is that you have to set the proper font name. However, this is unreliable. The bold version of Cochin is Cochin-Bold, but the bold version of ArialMT is not ArialMT-Bold but Arial-BoldMT, so it obviously does not suffice to append -Bold. (The bold version of a custom font could also have a totally different name).

What I can do is finding all fonts for the family of my given font.

__block UIFont *font = myLabel.font;
[[UIFont fontNamesForFamilyName:font.familyName] enumerateObjectsUsingBlock:^(NSString *fontName, NSUInteger idx, BOOL *stop) {
    if ([fontName rangeOfString:@"bold" options:NSCaseInsensitiveSearch].location != NSNotFound) {
        font = [UIFont fontWithName:fontName size:font.pointSize];
        *stop = YES;
    }
}];
myLabel.font = font;

But this does not work reliably. I can easily get a BoldItalic version. I could improve my check to avoid this, but it is not really a good solution.

Maybe CoreText can help here?

Answer 1

Maybe CoreText can help here?

CoreText uses its own font system, CTFont. If you're using that, you can do what you want:

CTFontRef font = CTFontCreateWithName((__bridge CFStringRef)name, size, NULL);
CTFontRef boldFont = CTFontCreateCopyWithSymbolicTraits(font, 0.0, NULL, kCTFontBoldTrait, kCTFontBoldTrait);

I suppose you could then get the name of the derived bold font:

CFStringRef boldName = CTFontCopyPostScriptName(boldFont);

...and use it to create a new UIFont:

UIFont *ret = [UIFont fontWithName:(NSString *)boldName size:size];

I don't know how quick this would be, but you could do it on app launch then cache the names.