IOS Debugger Agent

iOS Debugger Agent

Build and run iOS projects on a booted simulator, interact with the UI, and capture logs for debugging — via the flowdeck skill, which is this lacquer's canonical source of truth for exact FlowDeck syntax. This skill is a thin, scenario-specific wrapper around it, not a competing source of commands. If a command below errors or you're unsure of a flag, consult flowdeck's resources/ docs or run flowdeck <command> --help rather than guessing — never fall back to xcrun/simctl/xcodebuild.

Overview

FlowDeck ties build, install, and launch together (flowdeck run), and streams logs from the running app rather than querying the OS unified log. There is no need to discover DerivedData paths, hand-construct xcodebuild destinations, or spawn log stream predicates — FlowDeck's config-first workflow and app-tracking model replace all of that.

Prerequisites

• FlowDeck CLI installed (flowdeck --version)
• Project with .xcodeproj or .xcworkspace
• A saved FlowDeck config, or enough context to create one (flowdeck context --json)

Core Workflow

1) Check for a saved config first

flowdeck config get --json

If a config exists, use bare commands (flowdeck build, flowdeck run, etc.) for the rest of this workflow. If not, discover and create one:

flowdeck context --json
flowdeck config set -w <workspace> -s <scheme> -S "<simulator>"

2) Discover the booted simulator (if you need a specific one)

flowdeck simulator list --json

Check each entry's state field for "Booted". If none are booted and you need a specific device, boot one by UDID (boot takes a UDID, not a name):

flowdeck simulator boot <udid>

3) Build the project

flowdeck build

Add -w <workspace> -s <scheme> -S "<simulator>" only if no config is saved and you're not overriding it.

4) Install and launch the app

flowdeck run

This builds, installs, and launches in one step, returning an App ID. To launch an existing build without rebuilding:

flowdeck run --no-build

There is no standalone "install only" verb for simulators — FlowDeck ties install to launch by design. (Physical devices are the exception: flowdeck device install <udid> <path-to-app> installs without launching — see resources/device.md in the flowdeck skill.)

5) Capture logs

Either launch with logs streaming immediately:

flowdeck run --log     # run with run_in_background: true

Or attach to an already-running app:

flowdeck apps                 # find the App ID
flowdeck logs <app-id>        # run with run_in_background: true — this is a continuous stream

Never use xcrun simctl spawn … log, log show, or log stream — FlowDeck captures all print() and OSLog output in this one stream.

UI Interaction

Take a screenshot

Screenshots are primarily session-based, not one-off:

flowdeck ui simulator session start -S "<sim>" --json
# Read the `latest_screenshot` path from the JSON response with the Read tool

For a single one-off capture when no session is running:

flowdeck ui simulator screen -S "<sim>" --output /tmp/screenshot.png

Record video

flowdeck simulator record -S "<sim>"                      # record until Ctrl+C, or add --duration 10s

For frame-by-frame capture (e.g. validating an animation) instead of a video file, use flowdeck simulator frames -S "<sim>" (contact sheet by default, --images for full-res PNGs per frame).

Open a URL in the simulator

flowdeck ui simulator open-url "myapp://deeplink" -S "<sim>"

Send a push notification

flowdeck simulator push notification.apns -b com.example.MyApp -S "<sim>"

notification.apns must contain an aps key. -b/--bundle-id is optional if the payload includes a Simulator Target Bundle key.

Troubleshooting

• Build fails: Run flowdeck context --json or flowdeck project schemes to confirm the scheme name. On failure, flowdeck build prints the extracted reason and a Full log: <path> line — read that file rather than rerunning with -v/--verbose.
• App won't launch: Check flowdeck simulator app info <bundle-id> -S "<sim>" for bundle metadata, or flowdeck apps to see what FlowDeck currently has tracked.
• Simulator not found: flowdeck simulator list --available-only; create one with flowdeck simulator create -n "<name>" --device-type "<type>" --runtime "<runtime>" if needed.
• Clean build: flowdeck clean, or flowdeck clean --all to clear all caches.

Common Commands Reference

For anything not covered above — hardware buttons, appearance, Dynamic Type, privacy grants, keychain, pasteboard, watch/phone pairing — see resources/simulator.md and resources/ui.md in the flowdeck skill.