How To Customize Strings in Swift? Old but Gold: NSAttributedString

Related: How To Use NSAttributedString in SwiftUI: Hack It!

We use NSAttributedString to create different styled texts in Swift. There are many options to modify in this class.

To understand how it works, let’s get started with a simple attributed string example.

let str = "Coffee Break Codes"	

var attribute = [NSAttributedString.Key: AnyObject]()
attribute[.font] = UIFont.systemFont(ofSize: 12)
attribute[.foregroundColor] = UIColor.black

let attributedStr = NSMutableAttributedString(string: str, attributes: attribute)

Here, we created an attributed string by adding font and color attributes to a static text.

Now, let’s change the attributes of a substring in a string.

Font & Size:

let str = "SwiftUI: change font of substring iPhone"

var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.font,
                    value: UIFont.boldSystemFont(ofSize: 22),
                    range: NSString(string: str).range(of: "iPhone"))

Use NSAttributedString.Key.font to change style and size.

Shadow:

let str = "SwiftUI: add shadow to the substring Batman"

let shadow = NSShadow()
shadow.shadowOffset = CGSize(width: 2, height: 2)
shadow.shadowBlurRadius = 4
shadow.shadowColor = UIColor.black
        
var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.shadow,
                    value: shadow,
                    range: NSString(string: str).range(of: "Batman"))

Use NSAttributedString.Key.shadow to add shadow.

Foreground Color:

let str = "SwiftUI: change color of substring: iOS in purple"
        
var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.foregroundColor,
                    value: UIColor.purple,
                    range: NSString(string: str).range(of: "iOS"))

Use NSAttributedString.Key.foregroundColor to change foreground color.

Background Color:

let str = "SwiftUI: change background color of substring Superman in red"
        
var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.backgroundColor,
                    value: UIColor.red,
                    range: NSString(string: str).range(of: "Superman"))

Use NSAttributedString.Key.backgroundColor to change background color.

Underline:

let str = "SwiftUI: underline a specific keyword: Coffee, nothing else!"
        
var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.underlineStyle,
                    value: NSUnderlineStyle.single.rawValue,
                    range: NSString(string: str).range(of: "Coffee"))

Use NSAttributedString.Key.underlineStyle to add underline.

Link:

let str = "SwiftUI: add link to a substring Click Here"
        
var attributedStr = NSMutableAttributedString(string: str)
attributedStr.addAttribute(
                    NSAttributedString.Key.link,
                    value: "coffeebreakcodes.com",
                    range: NSString(string: str).range(of: "Click Here"))

Use NSAttributedString.Key.link to add link.