NSAttributedStringBuilder

Composing NSAttributedString with SwiftUI-style syntax, powered by Result Builder.

Project Link: https://github.com/ethanhuang13/NSAttributedStringBuilder

Features

How to use?

Traditionally we compose a NSAttributedString like this:

let mas = NSMutableAttributedString(string: "")
mas.append(NSAttributedString(string: "Hello world", attributes: [.font: UIFont.systemFont(ofSize: 24), .foregroundColor: UIColor.red]))
mas.append(NSAttributedString(string: "\n"))
mas.append(NSAttributedString(string: "with Swift", attributes: [.font: UIFont.systemFont(ofSize: 20), .foregroundColor: UIColor.orange]))

Now, with NSAttributedStringBuilder, we can use SwiftUI-like syntax to declare NSAttributedString:

let attributedString = NSAttributedString {
    AText("Hello world")
        .font(.systemFont(ofSize: 24))
        .foregroundColor(.red)
    LineBreak()
    AText("with Swift")
        .font(.systemFont(ofSize: 20))
        .foregroundColor(.orange)
}

Requirements

Xcode 12.5. This project uses Swift 5.4 feature Result Builder.

Installation

Swift Package

Open your project in Xcode 12, navigate to Menu -> Swift Packages -> Add Package Dependency and enter https://github.com/ethanhuang13/NSAttributedStringBuilder to install.

CocoaPods

Add pod 'NSAttributedStringBuilder13' to your Podfile.

SwiftUI Sample Project

Besides clearer NSAttributedString syntax, since NSAttributedStringBuilder uses Result Builder it also enables API to build components in UIViewRepresentable(which embeds UIView in a SwiftUI View).

Just like a SwiftUI Text takes a String as input, the purpose of AttributedText in the sample project is to take a NSAttributedString as input and render in SwiftUI.

To achieve this, AttributedText.swift uses @NSAttributedStringBuilder to support SwiftUI-style syntax:

Then using an AttributedText will be like:

Open the sample in /SwiftUISampleApp/AttributedTextSample.xcodeproj and check AttributedText. It uses UITextView, you can also use UILabel or NSTextView.

TODO

• Better tests for image attachment

Known Issue

• NSAttributedString does not support link color, therefore Link component with a .color() modifier has no effect. Alternatively you need to specify in UITextView.linkTextAttributes or .tintColor.

Others

Initially discussed on this Twitter thread. Some code are inspired by zonble🙏.