axe

README

axe

Command-line development tools for iOS simulators — live-preview SwiftUI views with hot-reload support, interactive simulator control, and view hierarchy inspection.

Install

curl -fsSL https://raw.githubusercontent.com/k-kohey/axe/main/install.sh | sh

Or download a binary manually from the Releases page.

The preview command requires idb_companion for headless simulator management:

brew install facebook/fb/idb-companion

VSCode Extension

A VSCode extension that enables interactive SwiftUI previews directly in VSCode / Cursor. See vscode-extension/README.md for details. Download the .vsix file from the Releases page, then:

• VS Code: code --install-extension axe-swiftui-preview-<version>.vsix
• Cursor: Cmd+Shift+P > "Install from VSIX..." and select the file

Development Setup

Install dependencies using mise:

mise install

Run & Test

# Run
mise run exec -- --help

# Test
mise run test

Known Issues

Hot Reload (preview --watch)

• Computed properties and methods are hot-reloaded: The parser extracts computed properties (var x: T { ... }) and methods (func) for @_dynamicReplacement. Generic methods (func foo<T>(...)), static/class methods, and initializers are not hot-reloaded. Stored properties (let, @State, @Published, etc.) cannot be dynamically replaced (memory layout constraint) and automatically trigger a full rebuild via skeleton comparison.
• Transitive dependency changes are not detected: The watcher tracks files that directly define types used in the target file. Changes to files used indirectly (e.g. a model's dependency) do not trigger a rebuild. Re-save the target file to force a reload.

Source Parsing

• Indirect protocol conformance is not detected: Conformance via protocol composition (e.g. struct Foo: MyProtocol where MyProtocol: View) is not recognized. Direct : View, SwiftUI.View, and extension-based conformance are all supported.

Preview Macro

• #Preview(traits:) is not supported: Display trait parameters such as #Preview(traits: .landscapeLeft) are ignored.
• Rendering may be incomplete in rare cases: The preview renderer uses setNeedsLayout + layoutIfNeeded instead of Apple's private _render(seconds:) synchronous rendering API, which can occasionally result in an incomplete frame capture.

Platform

• Apple Silicon only: The preview compiler targets arm64 exclusively. Intel Macs are not supported.