iOS Simulator Skill for Claude Code
Production-ready skill for building, testing, and automating iOS apps. 27 scripts optimized for both human developers and AI agents.
Xcode Build + Simulator Automation
This skill covers both sides of iOS development:
- Xcode builds via
xcodebuild— compile, test, and parse results with progressive error disclosure - Simulator interaction via
xcrun simctlandidb— semantic UI navigation, accessibility testing, device lifecycle
If you only need Xcode build tooling without the simulator scripts, see the plugin version: xclaude-plugin
Installation
Via Plugin Marketplace (Recommended)
In Claude Code:
/plugin marketplace add conorluddy/ios-simulator-skill
/plugin install ios-simulator-skill@conorluddy
Via Git Clone
# Personal installation
git clone https://github.com/conorluddy/ios-simulator-skill.git ~/.claude/skills/ios-simulator-skill
# Project installation
git clone https://github.com/conorluddy/ios-simulator-skill.git .claude/skills/ios-simulator-skill
Restart Claude Code. The skill loads automatically.
Prerequisites
- macOS 12+
- Xcode Command Line Tools (
xcode-select --install) - Python 3
- IDB (optional, for interactive features:
brew tap facebook/fb && brew install idb-companion) - Pillow (optional, for visual diffs:
pip3 install pillow)
Features
Xcode Build with Progressive Disclosure
The build_and_test.py script wraps xcodebuild with token-efficient output. A build returns a single summary line with an xcresult ID:
Build: SUCCESS (0 errors, 3 warnings) [xcresult-20251018-143052]
Then drill into details on demand:
python scripts/build_and_test.py --get-errors xcresult-20251018-143052
python scripts/build_and_test.py --get-warnings xcresult-20251018-143052
python scripts/build_and_test.py --get-log xcresult-20251018-143052
This keeps agent conversations focused — no walls of build output unless you ask for them.
Simulator Navigation via Accessibility
Instead of fragile pixel-coordinate tapping, all navigation uses iOS accessibility APIs to find elements by meaning:
# Fragile — breaks if UI changes
idb ui tap 320 400
# Robust — finds by meaning
python scripts/navigator.py --find-text "Login" --tap
The accessibility tree gives structured data (element types, labels, frames, tap targets) at ~10 tokens default output vs 1,600-6,300 tokens for a screenshot. See AI-Accessible Apps for more on why accessibility-first navigation matters for AI agents.
Screenshot Token Optimization
When screenshots are needed (visual verification, bug reports, diffs), the skill automatically resizes and compresses them to minimize token cost. Default output across all 27 scripts is 3-5 lines — 96% reduction vs raw tool output.
| Task | Raw Tools | This Skill | Savings | |------|-----------|-----------|---------| | Screen analysis | 200+ lines | 5 lines | 97.5% | | Find & tap button | 100+ lines | 1 line | 99% | | Login flow | 400+ lines | 15 lines | 96% |
All 27 Scripts
Every script supports --help and --json. See SKILL.md for the complete reference.
Build & Development
| Script | What it does | Key flags |
|--------|-------------|-----------|
| build_and_test.py | Build Xcode projects, run tests, parse xcresult bundles | --project, --scheme, --test, --get-errors, --get-warnings |
| log_monitor.py | Real-time log monitoring with severity filtering | --app, --severity, --follow, --duration |
Device State
| Script | What it does | Key flags |
|--------|-------------|-----------|
| appearance.py | Switch dark mode, dynamic type, locale, region | --theme, --text-size, --locale, --region, --reset |
| location.py | Simulate GPS coordinates and run built-in scenarios | --lat, --lng, --city, --gpx, --list-scenarios, --clear |
Navigation & Interaction
| Script | What it does | Key flags |
|--------|-------------|-----------|
| screen_mapper.py | Analyze current screen, list interactive elements | --verbose, --hints |
| navigator.py | Find and interact with elements semantically | --find-text, --find-type, --find-id, --tap, --enter-text |
| gesture.py | Swipes, scrolls, pinches, long press, pull to refresh | --swipe, --scroll, --pinch, --long-press, --refresh |
| keyboard.py | Text input and hardware button control | --type, --key, --button, --clear, --dismiss |
| app_launcher.py | Launch, terminate, install, deep link apps | --launch, --terminate, --install, --open-url, --list |
Testing & Analysis
| Script | What it does | Key flags |
|--------|-------------|-----------|
| accessibility_audit.py | WCAG compliance checking on current screen | --verbose, --output |
| visual_diff.py | Compare two screenshots for visual changes | --threshold, --output, --details |
| test_recorder.py | Automated test documentation with screenshots | --test-name, --output |
| app_state_capture.py | Debugging snapshots (screenshot, hierarchy, logs) | --app-bundle-id, --output, --log-lines |
| sim_health_check.sh | Verify environment (Xcode, simctl, IDB, Python) | — |
| model_inspector.py | Inspect Core Data / SwiftData models from project files | --project-path, --raw, --show-versions |
| container.py | Inspect app sandbox: list, cat, UserDefaults, Core Data, export | --ls, --cat, --userdefaults, --core-data-path, --export |
| hang_watcher.py (HangBuster) | Record + summarise os_log hang events with progressive disclosure (session mode + raw NDJSON + legacy stream); auto-restart on stream death, automatic disk-cap cleanup | --start [--raw-capture --max-size-mb N --no-gzip], --stop, --get-details, --list-sessions, --diff, --budget-tokens, --auto-sample (legacy: --watch, --since) |
| localization_audit.py | Audit .xcstrings catalogs for missing keys, unused keys, placeholder mismatches | --catalog, --source, --strict |
Permissions & Environment
| Script | What it does | Key flags |
|--------|-------------|-----------|
| clipboard.py | Copy text to simulator clipboard for paste testing | --copy, --test-name |
| status_bar.py | Override status bar (time, battery, network) | --preset, --time, --battery-level, --clear |
| push_notification.py | Send simulated push notifications | --bundle-id, --title, --body, --payload |
| privacy_manager.py | Grant, revoke, reset app permissions (13 services) | --bundle-id, --grant, --revoke, --reset |
Device Lifecycle
| Script | What it does | Key flags |
|--------|-------------|-----------|
| simctl_boot.py | Boot simulators with readiness verification | --name, --wait-ready, --timeout, --all, --type |
| simctl_shutdown.py | Gracefully shutdown simulators | --name, --verify, --all, --type |
| simctl_create.py | Create simulators by device type and OS version | --device, --runtime, --list-devices |
| simctl_delete.py | Delete simulators with safety confirmation | --name, --yes, --all, --old |
| simctl_erase.py | Factory reset without deletion | --name, --verify, --all, --booted |
Configuration
Every operational limit — timeouts, output caps, polling intervals, cache size, post-action delays — is tunable via an IOS_SIM_* environment variable. Defaults are tuned for local development on Apple Silicon. Raise them on slow CI runners, large monorepos, or accessibility audits over complex screens. Lower them when you need faster failure or tighter token budgets.
There's a universal tradeoff to keep in mind:
- Higher caps / longer timeouts → fewer false failures, more complete diagnostics, more tokens consumed by AI agents and slower failures when something is genuinely broken.
- Lower caps / shorter timeouts → faster feedback, tighter token usage, risk of silently dropped errors or premature timeouts on legitimately slow operations.
Boot & lifecycle timeouts
How long to wait on xcrun simctl operations.
| Variable | Default | Tradeoff |
|---|---|---|
| IOS_SIM_BOOT_TIMEOUT | 300 (s) | Wait for simulator readiness after boot. Lower → faster failure on broken sims. Higher → survives cold-start on slow CI runners (GitHub-hosted macOS can need 4–6 min). |
| IOS_SIM_BOOT_SUBPROCESS_TIMEOUT | 60 (s) | Timeout for the simctl boot call itself (before readiness polling starts). Rarely needs changing; bump only if you see Boot command timed out on resource-starved CI. |
| IOS_SIM_ERASE_TIMEOUT | 90 (s) | Wait for factory-reset verification. Larger simulators (lots of installed apps + data) can need more than the old 30s. |
| IOS_SIM_POLL_INTERVAL | 0.5 (s) | How often to re-check boot/erase state. Lower → more responsive (more CPU). Higher → quieter on slow CI but adds latency to “ready” detection. |
| IOS_SIM_STATE_SUBPROCESS_TIMEOUT | 15 (s) | Per-subprocess timeout in app_state_capture.py. Bump for apps with very large accessibility trees. |
Build & test output caps
build_and_test.py returns counts by default and full details via xcresult ID; these caps govern what's surfaced in human/JSON output before progressive disclosure kicks in.
| Variable | Default | Tradeoff |
|---|---|---|
| IOS_SIM_BUILD_SUMMARY_CAP | 15 | Errors / failed tests in the default text summary. Lower → terser default output. Higher → less need to chase xcresult IDs for context. |
| IOS_SIM_BUILD_VERBOSE_CAP | 100 | Errors / warnings in --verbose mode. Mostly relevant for monorepos or first builds with many fixable warnings. |
| IOS_SIM_BUILD_JSON_CAP | 50 | Max errors / failed tests in --json outp