Swift inspector

SimDeckInspectorAgent is a debug-only Swift package for UIKit and SwiftUI apps. It exposes richer hierarchy data and debug actions than accessibility alone.

Add the package

Add this local Swift package to your app:

packages/inspector-agent

Link the SimDeckInspectorAgent product only in debug builds.

Start it

SwiftUI:

#if DEBUG
import SimDeckInspectorAgent
#endif

@main
struct DemoApp: App {
    init() {
        #if DEBUG
        try? SimDeckInspectorAgent.shared.start()
        #endif
    }

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

UIKit:

func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
) -> Bool {
    #if DEBUG
    try? SimDeckInspectorAgent.shared.start()
    #endif
    return true
}

SwiftUI trees

Publish a SwiftUI root when you want the declared SwiftUI tree instead of only the backing UIKit views:

WindowGroup {
    ContentView()
        .simDeckPublishSwiftUIViewTree("ContentView", id: "app.root")
}

Tag important SwiftUI views so they are easy to find:

Text("Continue")
    .simDeckInspectorTag("continue-label", id: "onboarding.continue.label")

Then inspect:

simdeck describe <udid> --source swiftui --format agent
simdeck describe <udid> --source uikit --format agent

Debug actions

When the selected view supports it, the browser can:

• Read runtime properties.
• Set simple UIKit properties for debugging.
• Perform actions such as tap, focus, set text, or scroll.

These edits are temporary and meant for debugging, not persistent app state.

Direct protocol check

The Swift agent listens on 127.0.0.1:47370 and tries nearby ports if needed.

printf '{"id":1,"method":"Inspector.getInfo"}\n' | nc 127.0.0.1 47370

For protocol details, see Inspector protocol.

Shared hosts

For shared or remote hosts, bind deliberately and set an auth token:

try? SimDeckInspectorAgent.shared.start(
    configuration: .init(
        port: 47370,
        bindToLocalhostOnly: false,
        authToken: "debug-secret"
    )
)

Keep the default localhost binding for normal local development.

SwiftUI preview runner

This repo also includes an experimental preview runner for local development:

npm run preview:swiftui -- \
  --udid <booted-simulator-udid> \
  --file Sources/MyFeature/MyView.swift \
  --preview "Default" \
  --watch

It is intended for simulator-debuggable app targets and may need extra flags for complex projects.