How to Create SwiftUI iOS Development Plugins with the Build‑iOS‑Apps Plugin

The Build‑iOS‑Apps plugin in the openai/plugins repository is a modular Codex skill set that lets you scaffold, refactor, and debug SwiftUI iOS apps without leaving a Codex-driven workflow.

If you want to create SwiftUI iOS development plugins with the Build‑iOS‑Apps toolkit, start with the openai/plugins repo. It bundles discrete skills for UI patterns, performance audits, and simulator previews into a single plugin architecture that runs inside Codex.

Plugin Manifest and Registration

The top-level configuration lives in plugins/build-ios-apps/.codex-plugin/plugin.json.

{
  "name": "build-ios-apps",
  "version": "0.1.1",
  "description": "Build iOS apps with workflows for App Intents, SwiftUI UI work, …",
  "skills": "./skills/",
  "interface": {
    "displayName": "Build iOS Apps",
    "capabilities": ["Interactive","Read","Write"]
  }
}

This manifest registers the plugin with Codex, declares Interactive, Read, and Write capabilities, and points to the skills/ directory. (source: [plugins/build-ios-apps/.codex-plugin/plugin.json](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/.codex-plugin/plugin.json))

Skill Package Layout

Each skill follows a conventional layout under plugins/build-ios-apps/skills/<skill-name>/:

• SKILL.md — Human-readable workflow and quick-start.
• agents/ — Surface-specific agents such as openai.yaml.
• references/ — Markdown docs and Swift snippets.
• scripts/ — Optional helper scripts.
• assets/ — Optional icons and images.

(overview: [plugins/build-ios-apps/README.md](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/README.md))

Core SwiftUI Development Skills

swiftui-ui-patterns

The swiftui-ui-patterns skill is the central reference for state ownership, navigation, and sheet handling. Its SKILL.md enforces rules such as preferring @State and @Binding, adopting @Observable on iOS 17+, and falling back to ObservableObject on earlier OSes.

All component references are indexed in [skills/swiftui-ui-patterns/references/components-index.md](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/skills/swiftui-ui-patterns/references/components-index.md), which links to concrete implementation snippets for NavigationStack, TabView, and sheets.

swiftui-liquid-glass

The swiftui-liquid-glass skill provides boilerplate for Apple’s Liquid Glass APIs (iOS 26+). It walks through adding the LiquidGlass dependency via Swift Package Manager and using the GlassBackground wrapper, which internally handles #available(iOS 26, *) checks.

See [skills/swiftui-liquid-glass/SKILL.md](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/skills/swiftui-liquid-glass/SKILL.md) for the exact Package.swift snippet and Reference 22 for availability patterns.

swiftui-performance-audit

This skill combines three documents:

• profiling-intake.md — Describes how to attach Instruments and ETTrace.
• report-template.md — Auto-populated after an audit run.
• code-smells.md — Checklist matched against view code during the audit.

Together they generate a flame-graph and hotspot report via the optimizing-swiftui-performance helper script.

Simulator and Debug Tooling

ios-simulator-browser

The ios-simulator-browser skill runs a hot-reload preview server through a small script called swiftui-preview-browser.mjs. It exposes compiled previews over a local web server so you can see live UI updates directly inside the Codex UI.

Template entries live in [skills/ios-simulator-browser/scripts/templates/PreviewBrowserEntries.swift](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/skills/ios-simulator-browser/scripts/templates/PreviewBrowserEntries.swift).

MCP Wiring and Remote Debugging

The plugin ships with a Multi-Channel Protocol config in .mcp.json that connects the Codex runtime to XcodeBuildMCP. This enables build, run, and debug steps on a running simulator without leaving the Codex environment.

(source: [plugins/build-ios-apps/.mcp.json](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/.mcp.json))

Practical Code Examples

Adding a New SwiftUI Screen Using UI Patterns

import SwiftUI

// 1️⃣ Define the view-specific state – narrow as possible
struct SettingsView: View {
    @State private var enableNotifications = false   // local UI state
}

// 2️⃣ Use the recommended navigation pattern (NavigationStack)
struct ContentView: View {
    var body: some View {
        NavigationStack {
            List {
                NavigationLink("Settings", destination: SettingsView())
            }
            .navigationTitle("Demo App")
        }
    }
}

This follows Rule 30 in swiftui-ui-patterns: isolate UI state with @State and adopt NavigationStack as documented in references/navigationstack.md.

Enabling Liquid Glass in a New View

import SwiftUI
import LiquidGlass   // added via SwiftPM (see references/liquid-glass.md)

struct GlassyProfileView: View {
    var body: some View {
        GlassBackground {
            VStack {
                Text("Profile")
                    .font(.largeTitle)
                    .foregroundColor(.white)
                // … other UI …
            }
        } // GlassBackground automatically respects iOS 26+ availability
    }
}

Running a Performance Audit from the Skill

# From the repository root (Codex will invoke the skill)

codex run swiftui-performance-audit \
  --target MyApp \
  --device "iPhone 15 Pro" \
  --profile "MainFlow"

The skill will:

1. Launch Instruments with an ETTrace template.
2. Capture a flame-graph and feed it to optimizing-swiftui-performance.
3. Generate report-template.md with hotspots and suggested refactors.

(Automation details are in skills/swiftui-performance-audit/references/optimizing-swiftui-performance.md)

How to Use the Plugin in Your Own Codex Extension

1. Add the plugin as a dependency — Clone the openai/plugins repository and reference the plugins/build-ios-apps folder in your .codex-plugin manifest.

2. Invoke a skill via the Codex API:

   {
     "plugin": "build-ios-apps",
     "skill": "swiftui-ui-patterns",
     "intent": "Create a new TabView with NavigationStack",
     "params": { "projectName": "MyDemoApp" }
   }

3. Follow the skill’s quick-start found in its SKILL.md. The skill will generate scaffolding files, update your Xcode project, and optionally launch the simulator browser for live preview.

4. Iterate using the swiftui-view-refactor skill to break large views, or the swiftui-performance-audit skill to optimize after each iteration.

Summary

• The Build‑iOS‑Apps plugin provides a complete SwiftUI development pipeline inside Codex through modular skills.
• The manifest at .codex-plugin/plugin.json registers the plugin and points to the skills/ directory.
• swiftui-ui-patterns enforces modern state ownership and navigation conventions.
• swiftui-liquid-glass offers iOS 26+ glassy UI boilerplate with availability guards.
• swiftui-performance-audit automates profiling with ETTrace and generates a report-template.md.
• ios-simulator-browser delivers hot-reload previews via swiftui-preview-browser.mjs.
• MCP wiring in .mcp.json connects Codex to XcodeBuildMCP for simulator builds and debugging.

Frequently Asked Questions

What is the Build‑iOS‑Apps plugin and where is it located?

The Build‑iOS‑Apps plugin is a Codex toolkit inside the openai/plugins repository. It lives under plugins/build-ios-apps and bundles skills for designing, building, and debugging SwiftUI iOS applications.

How does the swiftui-ui-patterns skill handle state management?

According to the source code in [skills/swiftui-ui-patterns/SKILL.md](https://github.com/openai/plugins/blob/main/plugins/build-ios-apps/skills/swiftui-ui-patterns/SKILL.md), the skill prefers @State and @Binding for local UI state, recommends @Observable on iOS 17 and later, and falls back to ObservableObject for earlier OS versions.

Can I debug a simulator without leaving the Codex environment?

Yes. The plugin ships an .mcp.json configuration that wires Codex to XcodeBuildMCP, and the ios-debugger-agent skill handles debugging on a running simulator directly from the Codex interface.

What iOS version is required for the Liquid Glass skill?

The swiftui-liquid-glass skill targets iOS 26 and later. Its GlassBackground wrapper includes #available(iOS 26, *) checks so you can adopt the API safely while maintaining backward compatibility.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}