xcode-build-analyzer
Analyze Xcode build logs — timing, warnings, errors, slow compiles, and build history from DerivedData.
Best use case
xcode-build-analyzer is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Analyze Xcode build logs — timing, warnings, errors, slow compiles, and build history from DerivedData.
Teams using xcode-build-analyzer should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/xcode-build-analyzer/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How xcode-build-analyzer Compares
| Feature / Agent | xcode-build-analyzer | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Analyze Xcode build logs — timing, warnings, errors, slow compiles, and build history from DerivedData.
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
Related Guides
AI Agents for Coding
Browse AI agent skills for coding, debugging, testing, refactoring, code review, and developer workflows across Claude, Cursor, and Codex.
Best AI Skills for Claude
Explore the best AI skills for Claude and Claude Code across coding, research, workflow automation, documentation, and agent operations.
ChatGPT vs Claude for Agent Skills
Compare ChatGPT and Claude for AI agent skills across coding, writing, research, and reusable workflow execution.
SKILL.md Source
# Xcode Build Analyzer
Analyze Xcode build performance, warnings, errors, and history by reading DerivedData build logs on macOS.
## Requirements
- **macOS only** — reads from `~/Library/Developer/Xcode/DerivedData/`
- **Xcode** must be installed and have built at least one project
- **plutil**, **gunzip**, **sqlite3** (all pre-installed on macOS)
- Full Disk Access may be required depending on the process running queries
## Key paths
```
DERIVED_DATA=~/Library/Developer/Xcode/DerivedData
```
Each project has a folder named `<ProjectName>-<hash>` containing:
- `info.plist` — project workspace path and last accessed date
- `Logs/Build/LogStoreManifest.plist` — structured index of all builds (timing, status, warnings, errors)
- `Logs/Build/*.xcactivitylog` — gzip-compressed SLF build logs with per-step timing and full compiler output
> **Important:** All queries are read-only. Never modify DerivedData contents.
## List all projects in DerivedData
```bash
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
WORKSPACE="$(plutil -extract WorkspacePath raw "$dir/info.plist" 2>/dev/null || echo "unknown")"
LAST_ACCESS="$(plutil -extract LastAccessedDate raw "$dir/info.plist" 2>/dev/null || echo "unknown")"
echo "$NAME | $WORKSPACE | Last accessed: $LAST_ACCESS"
done
```
## Build history for a project
Parse the `LogStoreManifest.plist` for structured build data. This is the most reliable source — it contains timing, error/warning counts, and scheme info for every build without needing to decompress logs.
```bash
# Replace PROJECT_DIR with the project's DerivedData folder
# To find it: ls ~/Library/Developer/Xcode/DerivedData/ | grep -i "ProjectName"
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
MANIFEST="$PROJECT_DIR/Logs/Build/LogStoreManifest.plist"
plutil -convert json -o - "$MANIFEST" 2>/dev/null | python3 -c "
import json, sys
from datetime import datetime, timezone, timedelta
data = json.load(sys.stdin)
EPOCH = datetime(2001, 1, 1, tzinfo=timezone.utc)
builds = []
for uid, log in data.get('logs', {}).items():
start = log.get('timeStartedRecording', 0)
stop = log.get('timeStoppedRecording', 0)
duration = stop - start
obs = log.get('primaryObservable', {})
dt = EPOCH + timedelta(seconds=start)
builds.append({
'date': dt.strftime('%Y-%m-%d %H:%M'),
'duration': f'{duration:.1f}s',
'scheme': log.get('schemeIdentifier-schemeName', '?'),
'status': obs.get('highLevelStatus', '?'),
'errors': obs.get('totalNumberOfErrors', 0),
'warnings': obs.get('totalNumberOfWarnings', 0),
'analyzer': obs.get('totalNumberOfAnalyzerIssues', 0),
'file': log.get('fileName', ''),
})
builds.sort(key=lambda b: b['date'], reverse=True)
for b in builds:
status = {'S': 'OK', 'W': 'Warnings', 'E': 'Error'}.get(b['status'], b['status'])
print(f\"{b['date']} {b['duration']:>8s} {status:<10s} {b['errors']}E {b['warnings']}W {b['analyzer']}A [{b['scheme']}]\")
"
```
Replace `PROJECT_NAME` with the project name (case-insensitive grep match is fine).
**Status codes:** S = Succeeded, W = Succeeded with Warnings, E = Failed with Errors
## Latest build summary (all projects)
```bash
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
MANIFEST="$dir/Logs/Build/LogStoreManifest.plist"
[ -f "$MANIFEST" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
plutil -convert json -o - "$MANIFEST" 2>/dev/null | python3 -c "
import json, sys
from datetime import datetime, timezone, timedelta
data = json.load(sys.stdin)
EPOCH = datetime(2001, 1, 1, tzinfo=timezone.utc)
name = '$NAME'
latest = None
for uid, log in data.get('logs', {}).items():
start = log.get('timeStartedRecording', 0)
if latest is None or start > latest[0]:
latest = (start, log)
if latest:
start, log = latest
stop = log.get('timeStoppedRecording', 0)
obs = log.get('primaryObservable', {})
dt = EPOCH + timedelta(seconds=start)
duration = stop - start
status = {'S': 'OK', 'W': 'Warn', 'E': 'Err'}.get(obs.get('highLevelStatus', '?'), '?')
print(f\"{name:<30s} {dt.strftime('%Y-%m-%d %H:%M')} {duration:>6.1f}s {status:<5s} {obs.get('totalNumberOfErrors',0)}E {obs.get('totalNumberOfWarnings',0)}W\")
" 2>/dev/null
done
```
## Extract warnings and errors from a build log
```bash
# Find the latest xcactivitylog for a project
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
LATEST_LOG="$(ls -t "$PROJECT_DIR/Logs/Build/"*.xcactivitylog 2>/dev/null | head -1)"
# Extract warnings
gunzip -c "$LATEST_LOG" 2>/dev/null | strings | grep -E "\.swift:[0-9]+:[0-9]+: warning:" | sort -u
# Extract errors
gunzip -c "$LATEST_LOG" 2>/dev/null | strings | grep -E "\.swift:[0-9]+:[0-9]+: error:" | sort -u
```
## Warning summary (grouped by type)
```bash
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
LATEST_LOG="$(ls -t "$PROJECT_DIR/Logs/Build/"*.xcactivitylog 2>/dev/null | head -1)"
gunzip -c "$LATEST_LOG" 2>/dev/null | strings \
| grep -oE "warning: .*" \
| sed 's/\[.*//; s/'"'"'[^'"'"']*'"'"'//g' \
| sort | uniq -c | sort -rn | head -20
```
## Build step timing (find slow steps)
The xcactivitylog contains per-task `TaskMetrics` JSON with wall-clock duration in microseconds.
```bash
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
LATEST_LOG="$(ls -t "$PROJECT_DIR/Logs/Build/"*.xcactivitylog 2>/dev/null | head -1)"
gunzip -c "$LATEST_LOG" 2>/dev/null | strings \
| grep -o '{"wcDuration":[^}]*}' \
| python3 -c "
import json, sys
tasks = []
for line in sys.stdin:
try:
m = json.loads(line.strip())
tasks.append(m)
except: pass
tasks.sort(key=lambda t: t.get('wcDuration', 0), reverse=True)
print(f'Total tasks: {len(tasks)}')
print(f'Top 10 slowest (wall-clock microseconds):')
for i, t in enumerate(tasks[:10]):
wc = t['wcDuration']
rss = t.get('maxRSS', 0)
print(f' {i+1}. {wc/1000:.1f}ms (RSS: {rss/1024/1024:.1f}MB)')
"
```
## DerivedData disk usage
```bash
echo "Total DerivedData size:"
du -sh ~/Library/Developer/Xcode/DerivedData/ 2>/dev/null
echo ""
echo "Per project:"
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
SIZE="$(du -sh "$dir" 2>/dev/null | cut -f1)"
echo " $SIZE $NAME"
done | sort -rh
```
## Clean DerivedData for a project
Only suggest this when the user explicitly asks. This deletes the build cache and will force a full rebuild.
```bash
# Replace PROJECT_NAME with the project name
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
echo "Will delete: $PROJECT_DIR ($(du -sh "$PROJECT_DIR" 2>/dev/null | cut -f1))"
echo "Run: rm -rf \"$PROJECT_DIR\""
```
> **Warning:** Always confirm with the user before deleting. Suggest printing the size and path first.
## Build trend (all builds for a project over time)
```bash
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
MANIFEST="$PROJECT_DIR/Logs/Build/LogStoreManifest.plist"
plutil -convert json -o - "$MANIFEST" 2>/dev/null | python3 -c "
import json, sys
from datetime import datetime, timezone, timedelta
data = json.load(sys.stdin)
EPOCH = datetime(2001, 1, 1, tzinfo=timezone.utc)
builds = []
for uid, log in data.get('logs', {}).items():
start = log.get('timeStartedRecording', 0)
stop = log.get('timeStoppedRecording', 0)
builds.append((start, stop - start))
builds.sort()
if builds:
print(f'Builds tracked: {len(builds)}')
durations = [d for _, d in builds]
print(f'Fastest: {min(durations):.1f}s')
print(f'Slowest: {max(durations):.1f}s')
print(f'Average: {sum(durations)/len(durations):.1f}s')
print(f'Median: {sorted(durations)[len(durations)//2]:.1f}s')
print()
print('Timeline:')
for start, dur in builds:
dt = EPOCH + timedelta(seconds=start)
bar = '█' * max(1, int(dur / max(durations) * 30))
print(f' {dt.strftime(\"%m/%d %H:%M\")} {dur:>6.1f}s {bar}')
"
```
## Concurrency issues (Swift 6 readiness)
Extract Swift concurrency warnings that will become errors in Swift 6:
```bash
PROJECT_DIR="$(ls -d ~/Library/Developer/Xcode/DerivedData/PROJECT_NAME-* 2>/dev/null | head -1)"
LATEST_LOG="$(ls -t "$PROJECT_DIR/Logs/Build/"*.xcactivitylog 2>/dev/null | head -1)"
gunzip -c "$LATEST_LOG" 2>/dev/null | strings \
| grep -E "(data race|Sendable|actor-isolated|crossing into|concurrency)" \
| grep "warning:" \
| sort -u
```
## CLI builds (xcodebuild)
**Important:** `xcodebuild` CLI builds do **not** write to `LogStoreManifest.plist` or generate `.xcactivitylog` files unless you pass `-resultBundlePath`. This means the build history section above will only show Xcode IDE builds.
To detect CLI builds, check the build product timestamps and DerivedData info:
```bash
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
WORKSPACE="$(plutil -extract WorkspacePath raw "$dir/info.plist" 2>/dev/null || echo "unknown")"
# Detect if this is a worktree build (workspace path outside main project dir, e.g. /tmp/)
SOURCE=""
PROJ_DIR="$(dirname "$WORKSPACE")"
if [ -d "$PROJ_DIR" ] && git -C "$PROJ_DIR" rev-parse --is-inside-work-tree >/dev/null 2>&1; then
BRANCH="$(git -C "$PROJ_DIR" branch --show-current 2>/dev/null)"
IS_WORKTREE="$(git -C "$PROJ_DIR" rev-parse --is-inside-work-tree 2>/dev/null)"
MAIN_WORKTREE="$(git -C "$PROJ_DIR" worktree list 2>/dev/null | head -1 | awk '{print $1}')"
if [ "$PROJ_DIR" != "$MAIN_WORKTREE" ]; then
SOURCE=" (worktree: $BRANCH @ $PROJ_DIR)"
else
SOURCE=" (branch: $BRANCH)"
fi
fi
# Check Debug simulator product
APP="$(ls -dt "$dir/Build/Products/Debug-iphonesimulator/"*.app 2>/dev/null | head -1)"
if [ -n "$APP" ]; then
MTIME="$(stat -f '%Sm' -t '%Y-%m-%d %H:%M' "$APP" 2>/dev/null)"
VERSION=""
PLIST="$APP/Info.plist"
if [ -f "$PLIST" ]; then
SHORT="$(plutil -extract CFBundleShortVersionString raw "$PLIST" 2>/dev/null)"
BUILD="$(plutil -extract CFBundleVersion raw "$PLIST" 2>/dev/null)"
VERSION=" v${SHORT}(${BUILD})"
fi
echo "$NAME | Last build: $MTIME |$VERSION | $(basename "$APP")$SOURCE"
fi
# Check Release product
APP="$(ls -dt "$dir/Build/Products/Release-iphoneos/"*.app 2>/dev/null | head -1)"
if [ -n "$APP" ]; then
MTIME="$(stat -f '%Sm' -t '%Y-%m-%d %H:%M' "$APP" 2>/dev/null)"
echo "$NAME | Last release: $MTIME | $(basename "$APP")$SOURCE"
fi
done
```
> **Worktrees:** When building from a git worktree, Xcode creates a separate DerivedData entry (different hash) because the workspace path differs. The script above detects worktree builds by checking the git state of the workspace path and shows the branch name and worktree location.
### Combined build history (IDE + CLI)
To get a complete picture of all builds (both Xcode IDE and CLI), run both the LogStoreManifest parser and the build product check. The manifest gives detailed history for IDE builds; the product timestamps give the latest CLI build per configuration.
```bash
echo "=== IDE Builds (from LogStoreManifest) ==="
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
MANIFEST="$dir/Logs/Build/LogStoreManifest.plist"
[ -f "$MANIFEST" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
plutil -convert json -o - "$MANIFEST" 2>/dev/null | python3 -c "
import json, sys
from datetime import datetime, timezone, timedelta
data = json.load(sys.stdin)
EPOCH = datetime(2001, 1, 1, tzinfo=timezone.utc)
name = '$NAME'
for uid, log in sorted(data.get('logs', {}).items(), key=lambda x: x[1].get('timeStartedRecording', 0), reverse=True):
start = log.get('timeStartedRecording', 0)
stop = log.get('timeStoppedRecording', 0)
obs = log.get('primaryObservable', {})
dt = EPOCH + timedelta(seconds=start)
duration = stop - start
status = {'S': 'OK', 'W': 'Warn', 'E': 'Err'}.get(obs.get('highLevelStatus', '?'), '?')
scheme = log.get('schemeIdentifier-schemeName', '?')
print(f' {name:<25s} {dt.strftime(\"%Y-%m-%d %H:%M\")} {duration:>6.1f}s {status:<5s} [{scheme}] (IDE)')
" 2>/dev/null
done
echo ""
echo "=== CLI Builds (from build products) ==="
for dir in ~/Library/Developer/Xcode/DerivedData/*-*; do
[ -d "$dir" ] || continue
NAME="$(basename "$dir" | sed 's/-[a-z]*$//')"
for APP in "$dir/Build/Products/"*/*.app; do
[ -d "$APP" ] || continue
MTIME="$(stat -f '%Sm' -t '%Y-%m-%d %H:%M' "$APP" 2>/dev/null)"
CONFIG="$(basename "$(dirname "$APP")")"
echo " $NAME $MTIME [$CONFIG] $(basename "$APP") (CLI)"
done 2>/dev/null
done
```
## Notes
- `LogStoreManifest.plist` is the fastest way to get build history — no decompression needed
- `xcactivitylog` files are gzip-compressed SLF (Structured Log Format); use `gunzip -c` + `strings` for quick extraction
- Core Data timestamps: seconds since 2001-01-01 (`+ 978307200` to convert to Unix epoch)
- Build logs are kept until DerivedData is cleaned — Xcode may prune very old logs
- The `highLevelStatus` field: `S` = success, `W` = warnings, `E` = errors
- TaskMetrics `wcDuration` is in microseconds; `maxRSS` is in bytes
- All operations are **read-only** — never modify DerivedData while Xcode is runningRelated Skills
Profit Margin Analyzer
Analyze and optimize profit margins across your business. Identifies margin compression, pricing opportunities, and cost levers.
Pricing Strategy Analyzer
Analyze and optimize pricing for any product or service. Covers value-based, cost-plus, competitive, and tiered pricing models.
Portfolio Risk Analyzer
Complete investment portfolio risk management system. Analyze positions, calculate risk metrics, stress test scenarios, optimize allocations, and generate institutional-grade risk reports — all without external APIs.
Commercial Lease Analyzer
Analyze commercial leases (office, retail, industrial, warehouse) for hidden costs, unfavorable terms, and negotiation leverage. Use when reviewing a new lease, renegotiating a renewal, or comparing multiple lease options.
Go-to-Market Strategy Builder
Build a complete GTM plan for product launches, market entries, or expansion plays. Covers positioning, channel strategy, pricing, launch timeline, and success metrics.
Franchise Operations Analyzer
Evaluate franchise opportunities and manage multi-unit operations with data-driven frameworks.
Financial Due Diligence Analyzer
Run comprehensive financial due diligence on acquisition targets, investment opportunities, or partnership prospects. Built for PE firms, corporate development teams, and founders evaluating deals.
Energy Audit — Commercial Building Assessment
Run a full energy audit for commercial or industrial facilities. Identifies waste, models savings, and generates a prioritized retrofit roadmap with ROI timelines.
Employee Retention & Turnover Risk Analyzer
Diagnose why people leave. Fix it before they do.
Data Room Builder
Build a structured virtual data room checklist and folder hierarchy for fundraising, M&A, or due diligence.
Contract Analyzer
Analyzes contracts and agreements for risks, unusual terms, and missing clauses
Churn Risk Analyzer
Identify customers most likely to churn before they leave. Uses behavioral signals, usage patterns, and engagement data to score accounts and recommend retention actions.