How to make subscripts and superscripts using NSAttributedString?

Question

I need to make subscripts for chemistry formulas (H2O, Na^2+, etc)?

Is this possible to do with NSAttributedString, or is there an alternative/easier way to make sub

Answer 1

On iOS, I had missed the kCTSuperscriptAttributeName constant but had good results with font size and "baseline". It gives you a little more control too for less obedient fonts:

+ (NSAttributedString *)attributedStringForText:(NSString *)normalText andSuperscript:(NSString *)superscriptText textSize:(CGFloat)textSize
{
    UIFont *normalFont = [Styles mainFontWithSize:textSize];
    UIFont *superFont = [Styles mainFontWithSize:textSize / 2];

    NSMutableAttributedString *finalStr = [[NSMutableAttributedString alloc] initWithString:normalText attributes:@{NSFontAttributeName: normalFont}];

    NSAttributedString *superStr = [[NSAttributedString alloc] initWithString:superscriptText attributes:@{NSFontAttributeName: superFont, NSBaselineOffsetAttributeName:@(textSize/2)}];

    [finalStr appendAttributedString:superStr];

    return finalStr;
}