FeatureFlagKit

A flexible, protocol-based feature flag system for Swift applications.

Features

• 🎯 Type-Safe: Protocol-based design with Swift generics
• 💾 Persistent: Automatic storage via UserDefaults
• 🎨 SwiftUI Ready: Built-in UI components
• 🔧 Extensible: Easy to customize for any app
• 📱 Cross-Platform: iOS, macOS, tvOS, watchOS support

Installation

Swift Package Manager

Add FeatureFlagKit as a dependency in your Package.swift:

dependencies: [
    .package(url: "git@github.com:rickhohler/FeatureFlagKit.git", from: "1.0.0")
]

Or add it via Xcode: File → Add Packages → Enter repository URL

Quick Start

1. Define Your Feature Flags

import FeatureFlagKit

enum MyFeatureFlag: String, FeatureFlagProtocol {
    case darkMode
    case experimentalUI
    
    var displayName: String {
        switch self {
        case .darkMode: return "Dark Mode"
        case .experimentalUI: return "Experimental UI"
        }
    }
    
    var description: String {
        switch self {
        case .darkMode: return "Enable dark mode throughout the app"
        case .experimentalUI: return "Try the new experimental interface"
        }
    }
    
    var icon: String {
        switch self {
        case .darkMode: return "moon.fill"
        case .experimentalUI: return "sparkles"
        }
    }
}

2. Create a Manager

@MainActor
class AppFeatureFlags {
    static let shared = FeatureFlagManager<MyFeatureFlag>(
        storageKey: "com.myapp.featureFlags"
    )
}

3. Use in SwiftUI

struct SettingsView: View {
    @ObservedObject var manager = AppFeatureFlags.shared
    
    var body: some View {
        Form {
            Section("Experimental Features") {
                ForEach(MyFeatureFlag.allCases) { feature in
                    FeatureFlagToggleView(
                        feature: feature,
                        isEnabled: Binding(
                            get: { manager.isEnabled(feature) },
                            set: { manager.setEnabled(feature, enabled: $0) }
                        )
                    )
                }
            }
        }
    }
}

4. Check Flags in Code

if AppFeatureFlags.shared.isEnabled(.darkMode) {
    // Show dark mode UI
}

Advanced Usage

Default Values

Set features to be enabled by default:

var defaultValue: Bool {
    switch self {
    case .darkMode: return true  // Enabled by default
    case .experimentalUI: return false
    }
}

Feature Configuration

Add configuration screens for complex features:

var hasConfiguration: Bool {
    switch self {
    case .experimentalUI: return true
    default: return false
    }
}

Manager API

// Check if enabled
manager.isEnabled(.darkMode)

// Enable/disable
manager.setEnabled(.darkMode, enabled: true)

// Toggle
manager.toggle(.darkMode)

// Reset to defaults
manager.resetToDefaults()

Requirements

• Swift 5.10+
• iOS 15.0+ / macOS 12.0+ / tvOS 15.0+ / watchOS 8.0+

License

MIT License - See LICENSE file for details

Author

Rick Hohler