📐 ScaleKit

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ScaleKit is a lightweight Swift Package that automatically scales UI components such as fonts, paddings, and view sizes based on the screen size of various iPhone devices.
The default base device is iPhone 15 Pro Max, and you can explicitly choose other base devices.

🚀 Features

Screen-diagonal-based dynamic scaling
.scaled extensions for CGFloat, Double, Int, and Float
Works seamlessly with both SwiftUI and UIKit
Concurrency-safe using @MainActor

📦 Installation

Swift Package Manager (SPM)

Xcode →
File > Add Packages →
Enter: https://github.com/indextrown/ScaleKit.git

✅ Usage

SwiftUI

// App.swift
import SwiftUI
import ScaleKit

@main
struct TestApp: App {

    init() {
        // 1. Set screen size once at app launch
        DynamicSize.setScreenSize(UIScreen.main.bounds)

        // 2. Or explicitly set a different base device
        DynamicSize.setScreenSize(UIScreen.main.bounds, baseDevice: .iPhone14ProMax)
    }

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

// ContentView.swift
import SwiftUI
import ScaleKit

struct ContentView: View {
    var body: some View {
        Text("Start")
            .font(.system(size: 18.scaled))
            .padding(12.0.scaled)
            .frame(width: 100.scaled, height: 50.scaled)
    }
}

UIKit

import UIKit
import ScaleKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    
    var window: UIWindow?
    
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let windowScene = (scene as? UIWindowScene) else { return }
        DynamicSize.setScreenSize(windowScene.screen.bounds)

        let label = UILabel()
        label.font = .systemFont(ofSize: 18.scaled)
        label.layer.cornerRadius = 12.scaled
    }
}

⚠️ Important

Make sure to call the following method once at app launch:

DynamicSize.setScreenSize(UIScreen.main.bounds)

In SwiftUI, call it inside the App struct’s init().
In UIKit, call it in SceneDelegate or AppDelegate.

🧠 Scaling Formula

Default Base Device: iPhone 15 Pro Max (430 x 932pt)

scaleFactor = √(screenWidth² + screenHeight²) / √(430² + 932²)
scaledSize = baseSize × scaleFactor

🔧 Structure

DynamicSize: Sets screen size and calculates scale factor
.scaled: Extensions for Int, Double, Float, and CGFloat

📂 Folder Structure

Sources/
└── ScaleKit/
    ├── DynamicSize.swift
    ├── DynamicSize+BaseDevice.swift
    └── Scaled+Extensions.swift

📄 License

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction...

Made with 💻 by @donghyeon-kim

ScaleKit

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