ios-android-logs

iOS and Android Logs for Capacitor Apps

Pick the log channel that actually carries the message you need, filter to the app, capture to a file, hand off to diagnosis.

When to Use

TRIGGER when:

User asks how to view, stream, filter, or save device/simulator logs.
console.log output or ⚡️ Capacitor lines are missing on iOS/Android.
User needs a crash report (.ips, tombstone, ANR) from a device or simulator.
Logcat or the unified log is too noisy; user wants only their app or plugin.
A log command fails or misbehaves: --level error still shows everything, unable to find utility "devicectl", Error: Unexpected argument 'log', adb: no devices/emulators found.

Do not use:

Interpreting the error and fixing the app -> debugging-capacitor.
Production crash/ANR reporting (Sentry, Crashlytics, Datadog) -> capacitor-native-observability.
AI agent log streaming via MCP servers -> capacitor-mcp.
CPU/memory profiling -> capacitor-performance.
UIScene lifecycle migration -> capacitor-uiscene-migration.

Where Capacitor Output Goes (the main trap)

Source	iOS	Android
Capacitor bridge messages (`⚡️ Loading app at ...`, `⚡️ To Native ->`, errors)	stdout only (`print`)	logcat tag `Capacitor` and `Capacitor/<Sub>`
JS `console.log/warn/error` mirrored natively	stdout as `⚡️ [log] - ...`	logcat tag `Capacitor/Console` as `File: ... - Line N - Msg: ...`
JS console, full fidelity (objects, stack traces)	Safari Web Inspector	`chrome://inspect`
Plugin/app code using `os.Logger` / `NSLog`	unified log (Console.app, `log stream`)	n/a
Plugin code using `android.util.Log` / Capacitor `Logger`	n/a	logcat
Native crash	`.ips` crash report	`FATAL EXCEPTION` in logcat + crash buffer; tombstone for native code

Consequences:

On iOS, Console.app and log stream will not show Capacitor's ⚡️ lines or mirrored JS console. Use Xcode's console, xcrun simctl launch --console-pty, or xcrun devicectl device process launch --console.
Mirroring obeys loggingBehavior (none | debug | production, default debug): Release builds produce no Capacitor logs unless set to production.
The iOS process name is the executable (App in the Capacitor template), not the display name. Filter with process == "App".

Quick Commands

# iOS Simulator: Capacitor + JS console (stdout), relaunching the app
xcrun simctl launch --console-pty --terminate-running-process booted com.example.app

# iOS Simulator: unified log for the app (os_log / NSLog / system messages)
xcrun simctl spawn booted log stream --level debug --predicate 'process == "App"'

# iPhone: install + launch with stdout attached (Xcode 15+ devicectl)
xcrun devicectl list devices
xcrun devicectl device process launch --console --terminate-existing --device <id> com.example.app

# iPhone: unified log snapshot of the last 10 minutes
sudo log collect --device-udid <udid> --last 10m --output /tmp/iphone.logarchive
log show /tmp/iphone.logarchive --predicate 'process == "App"' --info --debug

# Android: only this app (re-run after each app restart, PID changes)
adb logcat --pid="$(adb shell pidof -s com.example.app)"

# Android: Capacitor + JS console only
adb logcat -s Capacitor:V Capacitor/Console:V

# Android: crashes only
adb logcat -b crash

Procedure

Identify target: Simulator/emulator vs physical device; Debug vs Release; which layer emitted the message (table above).
Check connectivity: xcrun simctl list devices booted, xcrun devicectl list devices (device must be unlocked, trusted, Developer Mode on), adb devices -l.
Clear and reproduce: adb logcat -c on Android; on iOS start the stream before relaunching the app.
Filter early by process/PID, then by subsystem/tag, then by text. Never paste unfiltered system logs into a conversation.
Save to a file (> app.log, .logarchive, adb bugreport) when the user needs to share it; redact tokens, emails, and auth headers before sharing outside the team.
Hand off the relevant lines to debugging-capacitor for root-cause work.

Error Handling

Message	Fix
`--level error` still shows every message	`log stream --level` only understands `default`, `info`, `debug` (it sets the floor, not a ceiling). Filter errors with `--predicate 'messageType == error OR messageType == fault'`.
`xcrun: error: unable to find utility "devicectl"`	Active dev dir is Command Line Tools. `sudo xcode-select -s /Applications/Xcode.app/Contents/Developer`.
`Error: Unexpected argument 'log'` (devicectl)	`devicectl` has no log streaming subcommand. Use `--console` for stdout, Console.app or `log collect --device-udid` for unified logs.
`log collect` fails with a permission error	Run with `sudo`; device must be unlocked and trusted.
`No devices are booted.` (simctl)	`xcrun simctl boot "<device name>"` or open Simulator.
`adb: no devices/emulators found` / `unauthorized`	Enable USB debugging, accept the RSA prompt, `adb kill-server && adb start-server`.
`adb logcat --pid=` prints everything / errors	App not running so `pidof` returned nothing. Launch the app first.
No `Capacitor/Console` lines on Android	`loggingBehavior: 'none'`, or Release build with default `debug`.
JS logs show but objects print as `[object Object]`	Native mirroring stringifies; use the WebView inspector for structured output.

Verification

iOS sim: launch with --console-pty, see ⚡️ Loading app at capacitor://localhost and a test console.log('log-check') as ⚡️ [log] - log-check.
iOS device: same via devicectl device process launch --console.
Android: adb logcat -s Capacitor/Console:V shows Msg: log-check.
Unified log: a plugin Logger(subsystem: "com.example.app", category: "test").info("log-check") appears with --predicate 'subsystem == "com.example.app"' --level info.

References

Only load a reference when its topic is in play.

File	Load when
`references/ios-logs.md`	Unified log predicates, Console.app, `log collect`/`log show`, iOS crash reports via devicectl/Xcode, adding `os.Logger` to a plugin
`references/android-logs.md`	logcat buffers/formats/filters, Android Studio Logcat queries, ANRs, tombstones, bugreports, WebView (`chromium`) noise

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