Notch

A Dynamic Island for your Mac's notch, built from scratch in Swift.

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What it does

Collapsed: a slim pill hugging the hardware notch. Album art on the left, six audio-reactive bars dancing to whatever's playing on the right. The menu bar underneath stays fully clickable.
Expanded: hover and the pill morphs into a player with artwork, title, a draggable scrubber, and transport controls. The album art and bars travel between the two layouts (matchedGeometryEffect), so opening feels like one continuous shape-shift rather than a swap.

• Now Playing, from anywhere: reads the system's Now Playing data (the same source Control Center uses), with a Spotify Apple-Events fallback for macOS versions that lock MediaRemote down. Play/pause, skip, and seek from the notch.

• Real audio visualization: a CoreAudio process tap feeds six log-spaced bandpass filters (80 Hz to 7 kHz); each bar is a real frequency band with its own attack/release envelope. Not a canned animation.

• Screenshots tab: watches for new screenshots, pops a toast, optionally copies them straight to the clipboard and routes them into a tidy folder. Swipe horizontally on the trackpad to switch tabs.

  

  Take a screenshot → the notch pops a "copied to clipboard" toast; hover it to reveal the recent-screenshots strip.

• Stays out of the way: no Dock icon, no menu bar item. It pins itself across every Space (including full-screen apps) and ducks off-screen when Mission Control or App Exposé takes over.

Why it's interesting under the hood

This is not a menu-bar-app template. A few of the problems it solves:

Living on every Space. A normal floating panel vanishes during Space swipes and full-screen transitions. Notch attaches its panel to a private CGS overlay space so it stays glued to the top of the screen through trackpad Space swipes, full-screen apps, and Mission Control, and retracts into the "bezel" with a spring animation when a system overlay needs the screen.

Real-time audio analysis on a budget. macOS 14.2's AudioHardwareCreateProcessTap provides a public way to tap the system mixdown. The tap runs six direct-form-I biquads per sample on the realtime IO thread, publishes RMS-per-band through a lock-protected snapshot, and a 60 Hz main-thread tick shapes it through per-band dB windows and asymmetric envelope followers. The result: bars that visibly travel instead of teleporting.

Costing nothing at idle. Every loop in the app is gated or event-driven: the audio tap exists only while music plays, hover detection rides mouse-moved events instead of a poll, UI publishes are skipped when nothing visibly changed, and Spotify updates arrive via distributed notification. Idle CPU is ~0% (down from ~15% in an earlier naive version; see PR #1 for the hunt).

First-class trackpad feel. Two-finger horizontal swipes switch tabs (with haptic ticks), respecting natural-scrolling direction, and a gesture monitor keeps the panel from fighting the system during live Space swipes.

Getting started

git clone https://github.com/spitfiresb/notch.git
cd notch
./build.sh run

Requires macOS 14.2+ (for the audio tap; everything else degrades gracefully) and Xcode command-line tools. No Xcode project needed; it's a plain Swift Package driven by build.sh. See BUILD.md for the full build/run/debug workflow.

On first launch an onboarding window walks through the permissions it wants:

Permission	Used for	Optional?
Audio capture	The dancing bars (system audio tap)	Yes (bars fall back to a synthesized wiggle)
Automation (Spotify)	Track info + controls when MediaRemote is unavailable	Yes (if you don't use Spotify)
Screenshot folder access	The screenshots tab & toasts	Yes

Architecture

Sources/Notch/
├── main.swift, AppDelegate.swift      AppKit entry point; hover/overlay watchers
├── AppEnvironment.swift               Observable app state, service lifecycle & gating
├── Window/
│   ├── NotchPanel.swift               Borderless panel, NotchShape, swipe detection
│   └── SettingsWindowController.swift
├── Views/
│   ├── NotchRootView.swift            The blob: collapsed peek ↔ expanded morph
│   ├── Tabs.swift                     Music & Screenshots tabs, scrubber
│   ├── OnboardingView.swift           First-run permissions walkthrough
│   └── SettingsView.swift
└── Services/
    ├── AudioMeter.swift               CoreAudio process tap → 6-band levels
    ├── NowPlaying.swift               MediaRemote bridge + Spotify fallback
    ├── ScreenshotWatcher.swift        Screenshot detection & routing
    ├── SpaceAttacher.swift            Private CGS space pinning
    ├── TrackpadGestureMonitor.swift   Live-gesture detection
    ├── Permissions.swift              TCC checks & System Settings deep links
    └── SettingsStore.swift            Persisted preferences

A more detailed map lives in BUILD.md.

Status

Personal project, actively developed. Tested on Apple Silicon, macOS 26. Issues and ideas welcome.