Power & Performance with asc
Download performance metrics and diagnostic logs to monitor app performance indicators — launch time, hang rate, disk writes, memory use, battery life, termination, and animation hitches.
Authentication
asc auth login --key-id <id> --issuer-id <id> --private-key-path ~/.asc/AuthKey.p8How to Navigate (CAEOAS Affordances)
Every JSON response contains an "affordances" field with ready-to-run commands — IDs already filled in. Follow the affordances to drill down from metrics to diagnostics to logs.
App metrics → Diagnostics → Logs flow:
// 1. asc perf-metrics list --app-id app-1 → shows performance overview
{
"id": "app-1-LAUNCH-launchTime",
"category": "LAUNCH",
"latestValue": 1.5,
"affordances": {
"listAppMetrics": "asc perf-metrics list --app-id app-1"
}
}
// 2. asc diagnostics list --build-id build-1 → shows hotspots
{
"id": "sig-1",
"diagnosticType": "HANGS",
"weight": 45.2,
"affordances": {
"listLogs": "asc diagnostic-logs list --signature-id sig-1",
"listSignatures": "asc diagnostics list --build-id build-1"
}
}
// 3. asc diagnostic-logs list --signature-id sig-1 → shows call stacks
{
"id": "sig-1-0-0",
"bundleId": "com.example.app",
"callStackSummary": "main > UIKit > layoutSubviews",
"affordances": {
"listLogs": "asc diagnostic-logs list --signature-id sig-1"
}
}Typical Workflows
Check app performance at a glance
asc perf-metrics list --app-id 123456789 --prettyInvestigate a specific metric type
# Launch time only
asc perf-metrics list --app-id 123456789 --metric-type LAUNCH --pretty
# Hang rate only
asc perf-metrics list --app-id 123456789 --metric-type HANG --prettyCompare build-specific metrics
asc builds list --app-id 123456789 --output table
asc perf-metrics list --build-id build-abc --prettyDiagnose hangs in a build
# 1. List diagnostic signatures (hang hotspots)
asc diagnostics list --build-id build-abc --diagnostic-type HANGS --pretty
# 2. Drill into the top signature's call stacks
asc diagnostic-logs list --signature-id sig-1 --prettyFull investigation pipeline
# Start from builds
BUILD_ID=$(asc builds list --app-id APP_ID | jq -r '.data[0].id')
# Check performance metrics
asc perf-metrics list --build-id "$BUILD_ID" --pretty
# Find hang hotspots
asc diagnostics list --build-id "$BUILD_ID" --diagnostic-type HANGS --pretty
# Get call stacks for the heaviest signature
SIG_ID=$(asc diagnostics list --build-id "$BUILD_ID" --diagnostic-type HANGS \
| jq -r '.data | sort_by(-.weight) | .[0].id')
asc diagnostic-logs list --signature-id "$SIG_ID" --prettyPerformance Metric Categories
| Category | --metric-type value | What it measures |
|---|---|---|
| Launch | LAUNCH | App launch time |
| Hang | HANG | Main thread hang rate |
| Memory | MEMORY | Peak and average memory use |
| Disk | DISK | Disk write volume |
| Battery | BATTERY | Energy impact |
| Termination | TERMINATION | Background/foreground terminations |
| Animation | ANIMATION | Animation hitch rate |
Diagnostic Types
| Type | --diagnostic-type value | What it captures |
|---|---|---|
| Hangs | HANGS | Main thread hang signatures |
| Disk Writes | DISK_WRITES | Excessive disk write signatures |
| Launches | LAUNCHES | Slow launch signatures |
Reading Results
PerformanceMetric — one row per metric identifier (e.g. launchTime, peakMemory), flattened from the nested Xcode Metrics API. Key fields:
category— which metric group (LAUNCH, HANG, etc.)latestValue+unit— most recent measurementgoalValue— Apple's recommended targetparentType—"app"or"build"(tells you whether this came from app-level or build-level metrics)
DiagnosticSignatureInfo — a recurring issue pattern ranked by weight (% of occurrences). Higher weight = more impactful. insightDirection of "UP" means the issue is getting worse.
DiagnosticLogEntry — individual log with device metadata and callStackSummary (top 5 frames joined with >).
Full Command Reference
See commands.md for all flags and examples.