iOS Simulator Skill

Build, test, and automate iOS applications using accessibility-driven navigation and structured data instead of pixel coordinates.

Quick Start

# 1. Check environment
bash scripts/sim_health_check.sh

# 2. Launch app
python scripts/app_launcher.py --launch com.example.app

# 3. Map screen to see elements
python scripts/screen_mapper.py

# 4. Tap button
python scripts/navigator.py --find-text "Login" --tap

# 5. Enter text
python scripts/navigator.py --find-type TextField --enter-text "[email protected]"

All scripts support --help for detailed options and --json for machine-readable output.

Navigation Strategy

Always prefer the accessibility tree over screenshots for navigation. The accessibility tree gives you element types, labels, frames, and tap targets — structured data that's cheaper and more reliable than image analysis.

Use this priority:

1. screen_mapper.py → structured element list (5-7 lines, ~10 tokens)
2. navigator.py --find-text/--find-type/--find-id → semantic interaction
3. Screenshots → only for visual verification, bug reports, or visual diff

Screenshots cost 1,600–6,300 tokens depending on size. The accessibility tree costs 10–50 tokens in default mode.

29 Production Scripts

Build & Development (2 scripts)

1. build_and_test.py - Build Xcode projects, run tests, parse results with progressive disclosure

• Build with live result streaming
• Parse errors and warnings from xcresult bundles
• Retrieve detailed build logs on demand
• Options: --project, --scheme, --clean, --test, --verbose, --json

1. log_monitor.py - Real-time log monitoring with intelligent filtering

• Stream logs or capture by duration
• Filter by severity (error/warning/info/debug)
• Deduplicate repeated messages
• Options: --app, --severity, --follow, --duration, --output, --json

Device State (2 scripts)

1. appearance.py - Control simulator appearance: dark mode, Dynamic Type size, and locale/region

• Toggle light/dark theme via xcrun simctl ui
• Set Dynamic Type size with friendly aliases (XS through AX5)
• Write locale and region defaults; optional app restart via --bundle-id
• RTL flagged automatically for ar/he/fa/ur/yi locales
• Options: --theme, --text-size, --locale, --region, --reset, --bundle-id, --udid, --json, --verbose

1. location.py - Simulate GPS coordinates, named city presets, and GPX scenario playback

• Fix a coordinate with --lat/--lng or pick a city with --city
• Play a built-in scenario (City Run, Freeway Drive, etc.) via --gpx <scenario>
• Animate multi-waypoint paths with configurable speed via --waypoints and --speed
• Clear simulated location with --clear; list available scenarios with --list-scenarios
• Options: --lat, --lng, --city, --gpx, --waypoints, --speed, --clear, --list-scenarios, --udid, --json, --verbose

Navigation & Interaction (5 scripts)

1. screen_mapper.py - Analyze current screen and list interactive elements

• Element type breakdown
• Interactive button list
• Text field status
• Options: --verbose, --hints, --json

1. navigator.py - Find and interact with elements semantically

• Find by text (fuzzy matching)
• Find by element type
• Find by accessibility ID
• Enter text or tap elements
• Options: --find-text, --find-type, --find-id, --tap, --enter-text, --json

1. gesture.py - Perform swipes, scrolls, pinches, and complex gestures

• Directional swipes (up/down/left/right)
• Multi-swipe scrolling
• Pinch zoom
• Long press
• Pull to refresh
• Options: --swipe, --scroll, --pinch, --long-press, --refresh, --json

1. keyboard.py - Text input and hardware button control

• Type text (fast or slow)
• Special keys (return, delete, tab, space, arrows)
• Hardware buttons (home, lock, volume, screenshot)
• Key combinations
• Options: --type, --key, --button, --slow, --clear, --dismiss, --json

1. app_launcher.py - App lifecycle management

• Launch apps by bundle ID
• Terminate apps
• Install/uninstall from .app bundles
• Deep link navigation
• List installed apps
• Check app state
• Pass launch arguments (--args) and environment variables (--env KEY=VALUE, injected as SIMCTL_CHILD_*) to the app on launch/restart
• Options: --launch, --terminate, --restart, --install, --uninstall, --open-url, --list, --state, --args, --env, --wait-for-debugger

Testing & Analysis (9 scripts)

1. accessibility_audit.py - Check WCAG compliance on current screen

• Critical issues (missing labels, empty buttons, no alt text)
• Warnings (missing hints, small touch targets)
• Info (missing IDs, deep nesting)
• Options: --verbose, --output, --json

1. visual_diff.py - Compare two screenshots for visual changes

• Pixel-by-pixel comparison
• Threshold-based pass/fail
• Generate diff images
• Options: --threshold, --output, --details, --json

1. test_recorder.py - Automatically document test execution

• Capture screenshots and accessibility trees per step
• Generate markdown reports with timing data
• Options: --test-name, --output, --verbose, --json

1. app_state_capture.py - Create comprehensive debugging snapshots

• Screenshot, UI hierarchy, app logs, device info
• Markdown summary for bug reports
• Options: --app-bundle-id, --output, --log-lines, --json

1. sim_health_check.sh - Verify environment is properly configured

• Check macOS, Xcode, simctl, IDB, Python
• List available and booted simulators
• Verify Python packages (Pillow)

1. model_inspector.py - Inspect Core Data and SwiftData models from project files

• Parse .xcdatamodeld packages (entities, attributes, relationships)
• Detect model versions and current active version
• Best-effort SwiftData @Model class extraction
• Raw source dump for any model on demand (--raw ModelName)
• Options: --project-path, --core-data-only, --swiftdata-only, --show-versions, --raw, --verbose, --json

1. container.py - Inspect app sandbox: files, UserDefaults, and Core Data store paths

• List data container files at configurable depth via --ls
• Read files with auto-detected plist decoding via --cat (large files cached)
• Dump UserDefaults as key=value or JSON via --userdefaults
• Locate .sqlite / .sqlite-wal / .sqlite-shm stores via --core-data-path
• Export full container snapshot via --export
• Options: --ls, --cat, --userdefaults, --core-data-path, --export, --udid, --json, --verbose

1. hang_watcher.py (HangBuster) - Record + summarise os_log hang events with progressive disclosure

• Session mode (HangBuster, agent-native): start a detached recorder, interact with the simulator, stop for a token-tight summary
• --start → returns a session ID; detached worker normalises + thresholds events on the fly
• --stop SESSION_ID → emits ~80–120 token L1 summary (header + top-N clusters + drill hint)
• --get-details SESSION_ID [--cluster N | --raw] → L2 full clusters or L3 per-event detail
• --list-sessions / --clear-sessions [--older-than 24h] / --diff A B (cross-session regression report)
• Filter pipeline: parse → normalise → threshold → bucket → cluster → aggregate → rank → format (in common/hang_pipeline.py)
• --budget-tokens N picks the densest level (L0/L1/L2) that fits; --terse forces L0
• --auto-sample captures a main-thread stack on first event per cluster (soft dependency: main_thread_sampler.py #62; graceful no-op if absent)
• Raw capture mode (full fidelity for `jq` exploration): skip the clustering pipeline, dump every matching log line verbatim to raw.ndjson
• --start --raw-capture [--max-size-mb 10] [--no-gzip] — spawns log stream --style ndjson
• Per-session size cap (--max-size-mb, default 10) — worker stops cleanly on cap; extras.truncated=true
• --stop gzips raw.ndjson → raw.ndjson.gz (~15–19× compression; --no-gzip opts out)
• --get-details SESSION_ID on a raw session prints the path with a zcat | jq ... hint
• Resilience (auto-restart on stream death): EOF or subprocess death triggers a stream_died event then a bounded restart with 2s backoff. After IOS_SIM_HANG_MAX_RESTARTS (default 3) the session is marked crashed, never left in stale running state. --list-sessions shows capture=Xs and restarts=N.
• Cleanup is automatic: TTL prune (IOS_SIM_HANG_SESSION_TTL_HOURS, default 24h) + aggregate cap (IOS_SIM_HANG_TOTAL_CAP_MB, default 100 MB, oldest-first eviction) both run on every --start.
• Legacy modes (unchanged for backward compat): --watch [--duration N] (live stream) and --since 5m (historical)
• Filters: --bundle-id (post-parse — hang capture stays simulator-global so RunningBoard/SpringBoard events are kept), --predicate (also via IOS_SIM_HANG_PREDICATE)
• All output supports --json; session storage at ~/.ios-simulator-skill/sessions/<id>/{meta.json,events.jsonl,summary.json,raw.ndjson.gz}

Quick start (summarised mode):

    SID=$(python scripts/hang_watcher.py --start --min-hang-ms 200)
    # ... interact with the simulator (open sheets, scroll, navigate) ...
    python scripts/hang_watcher.py --stop $SID                  # token-tight L1 summary
    python scripts/hang_watcher.py --get-details $SID --cluster 1  # drill into cluster 1
    python scripts/hang_watcher.py --diff $SID_BASELINE $SID    # cross-session regression

Quick start (raw capture + `jq` exploration):

    SID=$(python scripts/hang_watcher.py --start --raw-capture --max-size-mb 5)
    # ... interact with the simulator ...
    python scripts/hang_watcher.py --stop $SID
    # → "Session ...: raw mode, 737 lines, 0.96 MB → 0.05 MB gzipped"

    # Top processes by event count:
    zcat ~/.ios-simulator-skill/sessions/$SID/raw.ndjson.gz \
      | jq -s 'group_by(.processImagePath) | map({proc: (.[0].processImagePath | split("/") | last), n: length}) | sort_by(-.n) | .[:5]'

    # All RunningBoard assertion invalidations:
    zcat .../raw.ndjson.gz | jq -c 'select(.subsystem == "com.apple.runningboard" and (.eventMessage | startswith("Invalidating")))'

    # Hangs per minute:
    zcat .../raw.ndjson.gz | jq -r '.timestamp[:16]' | sort | uniq -c

1. localization_audit.py - Detect string catalog gaps, missing keys, and placeholder mismatches

• Report missing and needs_review/new keys per locale in .xcstrings catalogs
• Cross-reference catalog keys against Swift source (String(localized:) / NSLocalizedString) via --source
• Flag placeholder count mismatches (%d, %@, %s, %lld) across locales
• Legacy .strings and .stringsdict support via plistlib
• CI-friendly --strict exits 2 on any finding
• Options: --catalog, --source, --locale, --strict, --json, --verbose

Advanced Testing & Permissions (4 scripts)

1. clipboard.py - Manage simulator clipboard for paste testing

• Copy text to clipboard
• Test paste flows without manual entry
• Options: --copy, --test-name, --expected, --json

1. status_bar.py - Override simulator status bar appearance

• Presets: clean (9:41, 100% battery), testing (11:11, 50%), low-battery (20%), airplane (offline)
• Custom time, network, battery, WiFi settings
• Options: --preset, --time, --data-network, --battery-level, --clear, --json

1. push_notification.py - Send simulated push notifications

• Simple mode (title + body + badge)
• Custom JSON payloads
• Test notification handling and deep links
• Options: --bundle-id, --title, --body, --badge, --payload, --json

1. privacy_manager.py - Grant, revoke, and reset app permissions

• 13 supported services (camera, microphone, location, contacts, photos, calendar, health, etc.)
• Batch operations (comma-separated services)
• Audit trail with test scenario tracking
• Options: --bundle-id, --grant, --revoke, --reset, --list, --json

Simulator Discovery (2 scripts)

1. sim_list.py - List simulators with progressive disclosure

• Concise summary by default (total / available / booted)
• Full details on demand via cache IDs
• Filter by device type
• Suggest recommended simulators with --suggest
• 96% token reduction vs raw simctl list (57k → 2k tokens)
• Options: --get-details, --suggest, --device-type, --json

1. simulator_selector.py - Suggest the best simulator for the job

• Ranks candidates by recent use (from config.json), latest iOS, common test models, and boot status
• List all available simulators with --list
• Boot a selected simulator directly with --boot
• JSON output for programmatic use
• Options: --suggest, --list, --boot, --json

Device Lifecycle Management (5 scripts)

1. simctl_boot.py - Boot simulators with optional readiness verification

• Boot by UDID or device name
• Wait for device ready with timeout
• Batch boot operations (--all, --type)
• Performance timing
• Options: --udid, --name, --wait-ready, --timeout, --all, --type, --json

1. simctl_shutdown.py - Gracefully shutdown simulators

• Shutdown by UDID or device name
• Optional verification of shutdown completion
• Batch shutdown operations
• Options: --udid, --name, --verify, --timeout, --all, --type, --json

1. simctl_create.py - Create simulators dynamically

• Create by device type and iOS version
• List available device types and runtimes
• Custom device naming
• Returns UDID for CI/CD integration
• Options: --device, --runtime, --name, --list-devices, --list-runtimes, --json

1. simctl_delete.py - Permanently delete simulators

• Delete by UDID or device name
• Safety confirmation by default (skip with --yes)
• Batch delete operations
• Smart deletion (--old N to keep N per device type)
• Options: --udid, --name, --yes, --all, --type, --old, --json

1. simctl_erase.py - Factory reset simulators without deletion

• Preserve device UUID (faster than delete+create)
• Erase all, by type, or booted simulators
• Optional verification
• Options: --udid, --name, --verify, --timeout, --all, --type, --booted, --json

Common Patterns

Auto-UDID Detection: Most scripts auto-detect the booted simulator if --udid is not provided.

Device Name Resolution: Use device names (e.g., "iPhone 16 Pro") instead of UDIDs - scripts resolve automatically.

Batch Operations: Many scripts support --all for all simulators or --type iPhone for device type filtering.

Output Formats: Default is concise human-readable output. Use --json for machine-readable output in CI/CD.

Help: All scripts support --help for detailed options and examples.

Screenshot Sizing: Screenshots are resized to save tokens. Presets: full (3-4 tiles, ~5K tokens), half (1 tile, ~1.6K tokens, default), quarter (1 tile, ~800 tokens, less detail). Use quarter for quick visual checks, half for readable UI, full only when pixel-level detail matters. Scripts that capture screenshots (app_state_capture.py, test_recorder.py) default to half.

Typical Workflow

1. Verify environment: bash scripts/sim_health_check.sh
2. Launch app: python scripts/app_launcher.py --launch com.example.app
3. Analyze screen: python scripts/screen_mapper.py
4. Interact: python scripts/navigator.py --find-text "Button" --tap
5. Verify: python scripts/accessibility_audit.py
6. Debug if needed: python scripts/app_state_capture.py --app-bundle-id com.example.app

Configuration

Most operational limits can be tuned via environment variables. Defaults work for typical local development; raise them for slow CI runners, large monorepo builds, or accessibility audits on complex screens.

Example:

# Slow GitHub Actions runner: give boot 10 minutes
IOS_SIM_BOOT_TIMEOUT=600 python scripts/simctl_boot.py --wait-ready

Requirements

• macOS 12+
• Xcode Command Line Tools
• Python 3
• IDB (optional, for interactive features)

Documentation

• SKILL.md (this file) - Script reference and quick start
• README.md - Installation and examples
• CLAUDE.md - Architecture and implementation details
• references/ - Deep documentation on specific topics
• examples/ - Complete automation workflows

Key Design Principles

Semantic Navigation: Find elements by meaning (text, type, ID) not pixel coordinates. Survives UI changes.

Token Efficiency: Concise default output (3-5 lines) with optional verbose and JSON modes for detailed results.

Accessibility-First: Built on standard accessibility APIs for reliability and compatibility.

Zero Configuration: Works immediately on any macOS with Xcode. No setup required.

Structured Data: Scripts output JSON or formatted text, not raw logs. Easy to parse and integrate.

Auto-Learning: Build system remembers your device preference. Configuration stored per-project.

Use these scripts directly or let Claude Code invoke them automatically when your request matches the skill description.