How to convert between NSAttributedString and AttributedString

AttributedString is a new struct for styling string introduced in iOS 15.

• SwiftUI lacks the support for the old NSAttributedString but fully supports this new type.
• On the other hand, UIKit supported NSAttributedString but lacked the support of AttributedString in most APIs.

So, it is inevitable that you might need to convert between the two at some point.

In this article, I will show you how to convert NSAttributedString to AttributedString and back.

How to convert NSAttributedString to AttributedString

AttributedString has an initializer that accepts NSAttributedString.

AttributedString.init(_ nsStr: NSAttributedString)

So, you can use NSAttributedString in SwiftUI by converting it to AttributedString before use.

private var content: AttributedString {
    let string = "Attributed String"

    let attributes: [NSAttributedString.Key : Any] = [
        NSAttributedString.Key.foregroundColor: UIColor.systemPink,
        NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 40),
        NSAttributedString.Key.underlineStyle: NSUnderlineStyle.single.rawValue
    ]
    // 1
    let nsAttributedString = NSAttributedString(string: string, attributes: attributes)
    // 2
    let attributedString = AttributedString(nsAttributedString)
    return attributedString
}

var body: some View {
    // 3
    Text(content)
}

1 An NSAttributedString.
2 We create AttributedString out of the existing NSAttributedString.
3 SwiftUI Text can render AttributedString out of the box.

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How to convert AttributedString to NSAttributedString

NSAttributedString also has an initializer that accepts AttributedString.

convenience NSAttributedString.init(_ attrStr: AttributedString)

You can enjoy the new AttributedString in old UIKit components that don't support it by converting it to NSAttributedString before use.

let string = "Attributed String"

// 1
var attributedString = AttributedString(string)
attributedString.font = .boldSystemFont(ofSize: 40)
attributedString.foregroundColor = .systemPink
attributedString.underlineStyle = NSUnderlineStyle.single

let label = UILabel()
// 2
label.attributedText = NSAttributedString(attributedString)

1 Create an attributed string using a new API.
2 UILabel doesn't support setting the text using AttributedString, but we can easily convert AttributedString to NSAttributedString using a new initializer, NSAttributedString(attributedString).