Xcode Build Direct Skill

Xcode Build Direct

Build and manage iOS/macOS projects using native Xcode CLI tools. The core workflow uses Xcode/macOS command-line tools only; optional third-party helpers are called out separately when shown.

When to Use This Skill

Use this skill when:

Building iOS or macOS apps with Xcode
Running apps in iOS simulators
Managing simulator instances (boot, shutdown, list)
Taking screenshots of simulators
Capturing app logs
Running tests (unit or UI)
Automating UI interactions (tap, type, swipe)

Preference: Use direct CLI commands (xcodebuild, xcrun simctl) when you need portable, inspectable build evidence. If a project has a proven richer tooling path, such as XcodeBuildMCP, simulator automation, or a repo-local harness, follow that project-specific path.

Quick Start

1. Discover Project Structure

# List schemes in a workspace
xcodebuild -workspace /path/to/App.xcworkspace -list

# List schemes in a project
xcodebuild -project /path/to/App.xcodeproj -list

# Show build settings
xcodebuild -workspace /path/to/App.xcworkspace -scheme AppScheme -showBuildSettings

2. Find Available Simulators

# List all simulators
xcrun simctl list devices

# List as JSON (better for parsing)
xcrun simctl list devices --json

# List only available simulators
xcrun simctl list devices available

3. Build for Simulator

# List available simulators, then copy the UUID between parentheses.
xcrun simctl list devices available
UDID="PASTE-SIMULATOR-UUID-HERE"

# Build
xcodebuild \
  -workspace /path/to/App.xcworkspace \
  -scheme AppScheme \
  -destination "platform=iOS Simulator,id=$UDID" \
  -configuration Debug \
  -derivedDataPath /tmp/build \
  build

4. Install and Launch

# Find the built .app
APP_PATH=$(find /tmp/build -name "*.app" -type d | head -1)

# Install on simulator
xcrun simctl install $UDID "$APP_PATH"

# Launch app
xcrun simctl launch $UDID com.your.bundleid

5. Take Screenshot

xcrun simctl io $UDID screenshot /tmp/screenshot.png

Detailed References

For comprehensive command documentation, see:

CLI_REFERENCE.md - Full xcodebuild and xcrun simctl command reference
XCUITEST_GUIDE.md - UI automation via XCUITest (tap, type, gestures, element queries)

Common Patterns

Build + Run Workflow

# 1. Boot simulator
xcrun simctl boot $UDID 2>/dev/null || true

# 2. Build
xcodebuild -workspace App.xcworkspace -scheme App \
  -destination "platform=iOS Simulator,id=$UDID" \
  -derivedDataPath /tmp/build build

# 3. Find and install app
APP=$(find /tmp/build -name "*.app" -type d | head -1)
xcrun simctl install $UDID "$APP"

# 4. Launch with console output
xcrun simctl launch --console $UDID com.bundle.id

Log Capture

# Stream app logs (run in background)
/usr/bin/log stream \
  --predicate 'processImagePath CONTAINS[cd] "AppName"' \
  --style json &
LOG_PID=$!

# ... interact with app ...

# Stop logging
kill $LOG_PID

Running Tests

# Unit tests
xcodebuild -workspace App.xcworkspace -scheme App \
  -destination "platform=iOS Simulator,id=$UDID" \
  test

# Specific test class
xcodebuild -workspace App.xcworkspace -scheme App \
  -destination "platform=iOS Simulator,id=$UDID" \
  -only-testing "AppTests/MyTestClass" \
  test

UI Automation

For tapping, typing, and UI element queries, use XCUITest (Apple's native UI testing framework).

This is useful as a portable baseline because:

Native to iOS and maintained with Xcode
Full access to accessibility tree
Can wait for elements, handle animations
Integrates with Xcode test runner

See XCUITEST_GUIDE.md for complete patterns.

Quick example:

// In a UI test file
func testLogin() {
    let app = XCUIApplication()
    app.launch()

    // Type in text field
    app.textFields["email"].tap()
    app.textFields["email"].typeText("user@example.com")

    // Tap button
    app.buttons["Login"].tap()

    // Verify result
    XCTAssertTrue(app.staticTexts["Welcome"].exists)
}

Run UI tests:

xcodebuild -workspace App.xcworkspace -scheme AppUITests \
  -destination "platform=iOS Simulator,id=$UDID" \
  test

Session Configuration

Direct CLI tools don't maintain session state. Use environment variables or a config file:

# Set up session variables
export XCODE_WORKSPACE="/path/to/App.xcworkspace"
export XCODE_SCHEME="App"
export SIM_UDID="DD5E339B-468E-43C7-B219-54112C9D3250"
export APP_BUNDLE_ID="com.your.app"

# Use in commands
xcodebuild -workspace "$XCODE_WORKSPACE" -scheme "$XCODE_SCHEME" ...
xcrun simctl launch "$SIM_UDID" "$APP_BUNDLE_ID"

Troubleshooting

Build fails with "no matching destination"

# Check available destinations
xcodebuild -workspace App.xcworkspace -scheme App -showDestinations

# Use exact destination string from output

Simulator won't boot

# Check if already booted
xcrun simctl list devices | grep Booted

# Force shutdown and reboot
xcrun simctl shutdown $UDID
xcrun simctl boot $UDID

Can't find built .app

# Check derived data path you specified
ls -la /tmp/build/Build/Products/Debug-iphonesimulator/

# Or use default derived data
ls ~/Library/Developer/Xcode/DerivedData/

Direct CLI Baseline

XcodeBuildMCP and simulator automation tools can provide richer agent interfaces, persistent session state, and higher-level interactions when they are configured for the current project. This skill keeps the direct command equivalents visible so agents can still build, run, test, and capture evidence without depending on an MCP server.

| Feature | XcodeBuildMCP | This Skill | |---------|---------------|------------| | Build | build_sim({...}) | xcodebuild -workspace ... build | | List sims | list_sims() | xcrun simctl list devices | | Launch app | launch_app_sim({...}) | xcrun simctl launch $UDID $BUNDLE | | Screenshot | screenshot({...}) | xcrun simctl io $UDID screenshot | | Tap/Type | tap({x,y}), type_text({...}) | XCUITest framework | | Session state | Built-in | Environment variables |

Agent Skills: Xcode Build Direct

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