Swift CLI

A SwiftUI-inspired framework for building interactive command-line applications in Swift. This framework provides a declarative, reactive approach to creating terminal-based user interfaces with familiar SwiftUI concepts.

Features

• SwiftUI-like Syntax: Use familiar @State, @Environment, and view modifiers
• Interactive Controls: Buttons, text fields, and other interactive elements
• Layout System: VStack, HStack, and other layout containers
• Styling: Colors, padding, borders, and text formatting
• Event Handling: Keyboard input and focus management
• Cross-platform: Works on macOS and Linux

Requirements

• Swift 6.1+
• macOS 12.0+ or Linux

Installation

Add this package to your Package.swift:

dependencies: [
    .package(url: "https://github.com/pelagornis/swift-cli.git", from: "0.1.0")
]

Quick Start

import CommandLine

struct ContentView: View {
    @State private var count = 0

    var body: some View {
        VStack(spacing: 1) {
            Text("Counter: \(count)")
                .foregroundColor(.green)
                .bold()

            HStack {
                Button("Increment") {
                    count += 1
                }

                Button("Decrement") {
                    count -= 1
                }
            }
        }
        .padding()
        .border()
    }
}

Application(rootView: ContentView()).start()

Core Concepts

Views

Views are the building blocks of your UI. The framework provides several view types:

Text

Text("Hello, World!")
    .foregroundColor(.blue)
    .bold()
    .italic()

Buttons

Button("Click me") {
    print("Button pressed!")
}

// With custom label
Button(action: { /* action */ }) {
    HStack {
        Text("Custom")
        Text("Button")
    }
}

Text Fields

TextField { input in
    print("User entered: \(input)")
}

Layout

VStack (Vertical Stack)

VStack(spacing: 1) {
    Text("First item")
    Text("Second item")
    Text("Third item")
}

HStack (Horizontal Stack)

HStack {
    Text("Left")
    Spacer()
    Text("Right")
}

State Management

@State

struct MyView: View {
    @State private var isVisible = false
    @State private var counter = 0

    var body: some View {
        VStack {
            if isVisible {
                Text("Counter: \(counter)")
            }
            Button("Toggle") {
                isVisible.toggle()
                counter += 1
            }
        }
    }
}

@Environment

struct MyView: View {
    @Environment(\.foregroundColor) private var textColor

    var body: some View {
        Text("This text uses the environment color")
            .foregroundColor(textColor)
    }
}

Modifiers

Apply modifiers to customize the appearance and behavior of views:

Text("Styled Text")
    .foregroundColor(.red)
    .bold()
    .italic()
    .underline()
    .padding(2)
    .border()
    .background(.blue)

Available Modifiers

• Text Formatting: .bold(), .italic(), .underline(), .strikethrough()
• Colors: .foregroundColor(), .background()
• Layout: .padding(), .border(), .fixedFrame(), .flexibleFrame()
• Environment: .setEnvironment()

Application Lifecycle

import CommandLine

@MainActor
class MyApp {
    static func main() {
        Application(rootView: ContentView()).start()
    }
}

Advanced Features

Custom Controls

Create custom interactive controls by conforming to the Control protocol:

struct CustomControl: View, PrimitiveView {
    var body: some View {
        // Your custom implementation
    }

    func buildNode(_ node: Node) {
        // Setup your control
    }
}

Event Handling

Handle keyboard events and focus management:

Button("Interactive") {
    // Action when button is pressed
} hover: {
    // Action when button is hovered
}

Styling

Use colors and styling to create rich interfaces:

VStack {
    Text("Success")
        .foregroundColor(.green)
    Text("Warning")
        .foregroundColor(.yellow)
    Text("Error")
        .foregroundColor(.red)
}
.padding()
.border()
.background(.blue)

Examples

Simple Counter

struct CounterView: View {
    @State private var count = 0

    var body: some View {
        VStack(spacing: 1) {
            Text("Count: \(count)")
                .bold()

            HStack {
                Button("-") { count -= 1 }
                Button("+") { count += 1 }
            }
        }
        .padding()
        .border()
    }
}

Form Input

struct FormView: View {
    @State private var name = ""
    @State private var email = ""

    var body: some View {
        VStack(spacing: 1) {
            Text("Registration Form")
                .bold()
                .foregroundColor(.blue)

            HStack {
                Text("Name:")
                TextField { name = $0 }
            }

            HStack {
                Text("Email:")
                TextField { email = $0 }
            }

            Button("Submit") {
                print("Name: \(name), Email: \(email)")
            }
        }
        .padding()
        .border()
    }
}

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

swift-cli is under MIT license. See the LICENSE file for more info.