simulator-utils
iOS Simulator utility commands for screenshots, resizing, and common operations. Use these commands when taking simulator screenshots, resizing images for API compatibility, or performing common simulator operations.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/prisma-labs-dev/apple-skills --skill simulator-utils- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads simulator-utils automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Simulator Utilities
Quick reference for iOS Simulator commands. Use these patterns whenever working with simulators.
Screenshot with Auto-Resize (REQUIRED)
ALWAYS use this pattern when taking screenshots to avoid API errors:
# Single command: screenshot + resize
xcrun simctl io booted screenshot /path/to/screenshot.png && sips --resampleHeightWidthMax 1800 /path/to/screenshot.png
Why Resize?
- iPhone 17 simulator screenshots exceed 2000px
- Claude API rejects images >2000px in multi-image requests
sips --resampleHeightWidthMax 1800keeps images under limit
Resize Existing Screenshots
# Single file
sips --resampleHeightWidthMax 1800 /path/to/screenshot.png
# Multiple files
sips --resampleHeightWidthMax 1800 /path/to/*.png
# Batch resize all PNGs in directory
for f in /path/to/dir/*.png; do sips --resampleHeightWidthMax 1800 "$f"; done
Common Simulator Commands
Device Management
# List available simulators
xcrun simctl list devices available
# Boot specific device (prefer iPhone 17)
xcrun simctl boot "iPhone 17"
# Shutdown simulator
xcrun simctl shutdown booted
# Erase simulator (fresh state)
xcrun simctl erase "iPhone 17"
# Check booted device
xcrun simctl list devices | grep Booted
App Operations
# Install app
xcrun simctl install booted /path/to/App.app
# Launch app
xcrun simctl launch booted com.bundle.identifier
# Terminate app
xcrun simctl terminate booted com.bundle.identifier
# Uninstall app
xcrun simctl uninstall booted com.bundle.identifier
Screenshots
# Basic screenshot (NOT recommended - use resize pattern above)
xcrun simctl io booted screenshot /path/to/screenshot.png
# Screenshot with resize (RECOMMENDED)
xcrun simctl io booted screenshot /path/to/screenshot.png && sips --resampleHeightWidthMax 1800 /path/to/screenshot.png
# Screenshot to clipboard
xcrun simctl io booted screenshot - | pbcopy
Video Recording
# Start recording
xcrun simctl io booted recordVideo /path/to/video.mov
# Stop recording: Ctrl+C
Build Commands
# Build for simulator
xcodebuild -scheme SCHEME -project /path/to/Project.xcodeproj -destination 'platform=iOS Simulator,name=iPhone 17' build
# Build with output filtering (cleaner)
xcodebuild -scheme SCHEME -project /path/to/Project.xcodeproj -destination 'platform=iOS Simulator,name=iPhone 17' build 2>&1 | grep -E "(error:|warning:|BUILD)"
# Find built .app path
find ~/Library/Developer/Xcode/DerivedData -name "*.app" -path "*/Debug-iphonesimulator/*" -type d 2>/dev/null | head -1
Full Test Workflow
Complete pattern for build, install, launch, screenshot:
# 1. Build
xcodebuild -scheme SCHEME -project /path/to/Project.xcodeproj -destination 'platform=iOS Simulator,name=iPhone 17' build 2>&1 | grep -E "(error:|BUILD)"
# 2. Terminate existing instance (ignore errors)
xcrun simctl terminate booted com.bundle.identifier 2>/dev/null
# 3. Install
xcrun simctl install booted "/path/to/App.app"
# 4. Launch
xcrun simctl launch booted com.bundle.identifier
# 5. Wait for app to load
sleep 2
# 6. Screenshot with resize
xcrun simctl io booted screenshot /path/to/screenshot.png && sips --resampleHeightWidthMax 1800 /path/to/screenshot.png
Image Manipulation with sips
sips (Scriptable Image Processing System) is macOS built-in:
# Resize to max dimension (maintains aspect ratio)
sips --resampleHeightWidthMax 1800 image.png
# Resize to specific width
sips --resampleWidth 1000 image.png
# Resize to specific height
sips --resampleHeight 1000 image.png
# Get image dimensions
sips -g pixelWidth -g pixelHeight image.png
# Convert format
sips -s format jpeg image.png --out image.jpg
# Batch resize
sips --resampleHeightWidthMax 1800 *.png
Troubleshooting
"No devices are booted"
xcrun simctl boot "iPhone 17"
Screenshot too large for API
sips --resampleHeightWidthMax 1800 /path/to/screenshot.png
App won't launch
# Check bundle ID
xcrun simctl listapps booted | grep -A5 "CFBundleIdentifier"
# Reinstall
xcrun simctl uninstall booted com.bundle.identifier
xcrun simctl install booted /path/to/App.app
Simulator stuck
xcrun simctl shutdown all
xcrun simctl erase all
xcrun simctl boot "iPhone 17"
FAQ
What does the simulator-utils skill do?
iOS Simulator utility commands for screenshots, resizing, and common operations. Use these commands when taking simulator screenshots, resizing images for API compatibility, or performing common simulator operations.
How do I install simulator-utils?
Run npx skills add https://github.com/prisma-labs-dev/apple-skills --skill simulator-utils in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/simulator-utils/ (personal) or .claude/skills/simulator-utils/ (project).
Which AI agents can use simulator-utils?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is simulator-utils safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains simulator-utils?
It is published by prisma-labs-dev in prisma-labs-dev/apple-skills. It has 420 recorded installs.
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