iOS Engineer

Senior iOS engineer with expertise in building iOS applications and gathering visual feedback via iOS Simulator MCP integration.

Prerequisites

This skill requires external tools for simulator automation. Run the setup script:

.claude/plugins/ios-engineer/setup.sh

Required dependencies:

• Xcode - iOS development environment
• Homebrew - Package manager for macOS
• pyenv - Python version manager (fb-idb requires Python ≤3.13, not 3.14+)
• idb-companion - Facebook's iOS automation tool (brew tap facebook/fb && brew install idb-companion)
• fb-idb - Python client for IDB (pip install fb-idb)
• Node.js - For running MCP servers via npx

The setup script will configure pyenv to use Python 3.13.5 for this project via .python-version.

Visual Feedback Loop

This skill has access to iOS Simulator MCP tools that enable a powerful feedback loop:

Available MCP Tools

Tool	Purpose
mcp__ios-simulator__ui_view	Take screenshot and return image data for analysis
mcp__ios-simulator__ui_describe_all	Get full accessibility tree of current screen
mcp__ios-simulator__ui_describe_point	Describe element at specific coordinates
mcp__ios-simulator__ui_tap	Tap at coordinates (x, y)
mcp__ios-simulator__ui_swipe	Swipe gesture between coordinates
mcp__ios-simulator__ui_type	Type text into focused field
mcp__ios-simulator__screenshot	Save screenshot to file
mcp__ios-simulator__record_video	Record screen video
mcp__ios-simulator__launch_app	Launch app by bundle ID
mcp__ios-simulator__install_app	Install .app bundle

Screenshots Directory

Screenshots and recordings are saved to ios/.screenshots/ (gitignored). This directory:

• Keeps simulator artifacts organized within the iOS directory
• Is automatically used by the MCP server via IOS_SIMULATOR_MCP_DEFAULT_OUTPUT_DIR
• Can be cleaned up with ios/.screenshots/cleanup.sh (deletes files older than 7 days)
• Use ios/.screenshots/cleanup.sh --all to delete everything

Workflow: Build-See-Iterate

After making UI changes, follow this workflow:

1 Install Dependencies

xcodebuild -resolvePackageDependencies -project $PROJECT_NAME.xcodeproj -scheme $SCHEME

1. Build the app

Use mcp__xcodebuild tools or:
xcodebuild -scheme $SCHEME -destination 'platform=iOS Simulator,name=$SIMULATOR' build

2. Launch in simulator

mcp__ios-simulator__launch_app with bundle ID: $BUNDLE_ID

3. Navigate to the changed screen

• Use deep links: xcrun simctl openurl booted "$DEEP_LINK_SCHEME://..."
• Or use ui_tap to navigate through the UI

4. Capture and analyze

• Use ui_view to get screenshot for visual analysis
• Use ui_describe_all to verify accessibility tree
• Verify elements exist and are correctly positioned

When to Use Visual Feedback

Always use visual feedback for:

• New UI components or screens
• Layout changes (spacing, alignment, sizing)
• Animation or transition work
• Accessibility changes
• Dark mode / appearance changes

Optional for:

• Business logic changes with no UI impact
• GraphQL query/mutation changes (test via backend)
• Minor text changes (can verify via accessibility tree)

Core Patterns

Coding Best Practices

• Prefer composition over inheritance
• Extract reusable views into separate files

Accessibility

• Always set accessibilityIdentifier for testable elements
• Use semantic labels for VoiceOver
• Test with ui_describe_all to verify hierarchy

Code Quality Workflow

After completing ANY iOS work:

1. Build - Verify no compilation errors

2. Visual verification - Use simulator MCP tools to see your changes

3. Accessibility check - Use ui_describe_all to verify element tree

Simulator Automation Examples

Take screenshot after navigation

1. mcp__ios-simulator__launch_app(bundleId: "$BUNDLE_ID")
2. Wait 3 seconds for app load
3. mcp__ios-simulator__ui_view() - analyze the home screen
4. mcp__ios-simulator__ui_tap(x: 200, y: 400) - tap on element
5. mcp__ios-simulator__ui_view() - verify navigation worked

Verify accessibility

1. mcp__ios-simulator__ui_describe_all() - get full element tree
2. Verify expected elements are present with correct labels
3. Check for missing accessibility identifiers

Test dark mode

xcrun simctl ui booted appearance dark
# Then use ui_view to capture and compare