How to set up Sizes for iOS app testing?

Integrate Sizes by replacing your AppDelegate's window with SizesWindow in DEBUG mode, ensuring Auto Layout is used for UI updates. Shake the device to access the configuration UI for testing.

Sizes vs Xcode Previews: which is better?

Xcode Previews, introduced in Xcode 11, provide native support for UI testing across devices and are recommended over Sizes. Sizes is deprecated and less integrated with modern SwiftUI workflows.

Does Sizes work with SwiftUI?

No, Sizes is designed for UIKit apps with Auto Layout; for SwiftUI, use Xcode Previews which offer similar multi-device preview functionality out of the box.

Can I use Sizes in production?

No, Sizes is intended for debug-only use to avoid performance overhead; it should not be included in production builds as per the README's recommendations.

How to test font sizes with Sizes?

Sizes integrates with Dynamic Type; after setup, shake the device to open the UI and use the slider to preview different font sizes, with labels showing the font name as you adjust.

Is Sizes still maintained?

No, the author has deprecated Sizes in favor of Xcode Previews, and the repository is planned to be archived, so no future updates or bug fixes are expected.

Open-Awesome

Sizes

MITSwift0.3.0

A Swift library for iOS developers to preview apps across multiple device sizes, orientations, and font combinations.

GitHub

1.2k stars53 forks0 contributors

What is Sizes?

Sizes is a Swift library for iOS that allows developers to preview their app's UI across different device sizes, orientations, and font combinations. It solves the problem of manually testing layouts on multiple simulators, which is time-consuming and error-prone.

Target Audience

iOS developers who use Auto Layout and Dynamic Type, particularly those working on apps that need to support multiple device sizes and accessibility font scaling.

Value Proposition

Developers choose Sizes because it provides a quick, integrated way to validate UI changes across many configurations without leaving the app, reducing testing time and preventing layout bugs before shipping.

Overview

View your app on different device and font sizes

Use Cases

Best For

Testing iOS app layouts across iPhone and iPad screen sizes
Validating UI responsiveness when switching between portrait and landscape orientations
Checking Dynamic Type compatibility for accessibility font scaling
Debugging Auto Layout constraints in different device configurations
Quickly previewing UI changes without launching multiple simulators
Ensuring consistent typography across all supported font sizes

Not Ideal For

Teams already using Xcode Previews for SwiftUI or UIKit development
Projects that rely on manual frame-based layouts instead of Auto Layout
Environments requiring automated UI testing in CI/CD pipelines
Developers seeking actively maintained libraries for modern iOS versions

Pros & Cons

Pros

Efficient Multi-Device Testing

Allows quick validation of UI across various iOS device sizes and orientations without launching simulators, saving significant manual testing time.

Integrated Font Scaling

Supports testing Dynamic Type font sizes directly within the app, ensuring accessibility compliance and typography consistency.

Debug-Only Safety

Designed to be used only in DEBUG mode, preventing performance overhead in production builds and avoiding accidental inclusion.

Universal Device Support

Works on both iPhone and iPad devices, covering the full spectrum of iOS screen sizes for comprehensive testing.

Cons

Officially Deprecated

The README explicitly recommends deprecation due to Xcode 11's native Previews feature, making it obsolete for modern development workflows.

Auto Layout Dependency

Requires apps to use Auto Layout exclusively; projects with manual or alternative layout systems won't benefit from Sizes.

Setup Complexity

Involves replacing the app's main window with SizesWindow, which can interfere with custom window management or third-party integrations.

Limited to Debug Mode

Cannot be used for automated testing in production or CI/CD environments, restricting its utility to manual debugging only.

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