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FlowDeck CLI can stream real-time OSLog output from your running apps, making it easy to monitor app behavior without switching to Console.app.

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Streaming Logs

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Run with Log Streaming

The easiest way to stream logs is to use the --log flag when running: 
flowdeck run --workspace MyApp.xcworkspace --simulator "iPhone 16" --log
This builds, runs, and immediately starts streaming logs from your app.

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Stream Logs from Running App

If your app is already running, use the apps and logs commands: 
# List running apps
flowdeck apps

# Stream logs from an app
flowdeck logs <app-id>
Example: 
$ flowdeck apps
Running Apps:
  abc123  com.example.MyApp  iPhone 16 Pro
  def456  com.example.Test   iPad Pro

Use 'flowdeck logs <app-id>' to stream logs
Use 'flowdeck stop <app-id>' to stop an app

$ flowdeck logs abc123

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Using OSLog in Your Code

FlowDeck captures logs from Apple’s unified logging system (OSLog): 
import os

// Create a logger
let logger = Logger(subsystem: "com.example.myapp", category: "networking")

// Log at different levels
logger.debug("Debug: Starting request")
logger.info("Info: Request completed")
logger.warning("Warning: Slow response detected")
logger.error("Error: Request failed")

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Log Levels

LevelDescription
debugDetailed debugging information
infoGeneral informational messages
warningWarning conditions
errorError conditions
faultCritical errors

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Log Output

Logs are displayed with color-coded output based on log level: 
[DEBUG] 10:23:45.123 - Starting network request
[INFO]  10:23:45.234 - User logged in successfully
[WARN]  10:23:45.345 - API response slow (>2s)
[ERROR] 10:23:45.456 - Failed to parse JSON response

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Stopping Log Streaming

Press Ctrl+C to stop streaming logs.

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Stopping Running Apps

Stop an app that was launched by FlowDeck: 
flowdeck stop <app-id>

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Limitations

Log streaming is currently only available for simulators. For physical devices, use Console.app on macOS.

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Simulator Only

Due to Apple platform restrictions, FlowDeck can only stream logs from:
  • iOS Simulators
  • macOS apps (when running directly)

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For Physical Devices

Use macOS Console.app:
  1. Open Console.app
  2. Select your device from the sidebar
  3. Filter by your app’s process name or bundle identifier

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Tips

Use specific subsystem and category names in your OSLog calls to make filtering easier:
let logger = Logger(subsystem: "com.example.myapp", category: "auth")
Debug-level logs may not appear in Release builds. Use Info level or higher for logs you always want to see.

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Troubleshooting

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No Logs Appearing

  1. Ensure your app uses os.log or Logger APIs (not just print())
  2. Verify the app is running on a simulator
  3. Check that the debug session started successfully

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Too Many Logs

FlowDeck automatically filters to your app’s process. If you’re still seeing too many logs:
  • Use more specific subsystem/category names
  • Reduce debug-level logging in your code

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Logs Not Updating

If logs stop appearing:
  1. Check that the app is still running: flowdeck apps
  2. Restart log streaming: flowdeck logs <app-id>