How do I use subscript and superscript in Swift?

Question

I want my UILabel to display text in following manner 6.022*10²³. What functions does Swift have for subscript and superscript?

Answer 1

Most of the answers+examples are in ObjC, but this is how to do it in Swift.

let font:UIFont? = UIFont(name: "Helvetica", size:20) let fontSuper:UIFont? = UIFont(name: "Helvetica", size:10) let attString:NSMutableAttributedString = NSMutableAttributedString(string: "6.022*1023", attributes: [.font:font!]) attString.setAttributes([.font:fontSuper!,.baselineOffset:10], range: NSRange(location:8,length:2)) labelVarName.attributedText = attString 

This gives me:

In a more detailed explanation:

1. Get UIFont you want for both the default and superscript style, superscript must be smaller.
2. Create a NSMutableAttributedString with the full string and default font.
3. Add an attribute to the characters you want to change (NSRange), with the smaller/subscript UIFont, and the NSBaselineOffsetAttributeName value is the amount you want to offset it vertically.
4. Assign it to your UILabel

Hopefully this helps other Swift devs as I needed this as well.

Answer 2

As a different approach, I wrote a function that takes in a string where the exponents are prepended with ^ such as 2^2•3•5^2 and returns 2²•3•5²

func exponentize(str: String) -> String {      let supers = [         "1": "\u{00B9}",         "2": "\u{00B2}",         "3": "\u{00B3}",         "4": "\u{2074}",         "5": "\u{2075}",         "6": "\u{2076}",         "7": "\u{2077}",         "8": "\u{2078}",         "9": "\u{2079}"]      var newStr = ""     var isExp = false     for (_, char) in str.characters.enumerate() {         if char == "^" {             isExp = true         } else {             if isExp {                 let key = String(char)                 if supers.keys.contains(key) {                     newStr.append(Character(supers[key]!))                 } else {                     isExp = false                     newStr.append(char)                 }             } else {                 newStr.append(char)             }         }     }     return newStr } 

It's a bit of a brute force method, but it works if you don't want to deal with attributed strings or you want your string to be independent of a font.