SplitFlap

A macOS screensaver that simulates a split-flap mechanical display — the satisfying flip-card boards once found in airports and train stations around the world.

Built entirely in Swift using the native ScreenSaver framework and Core Animation.

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How it works

The display cycles through two alternating phases:

• Idle shuffle — individual panels drift to random characters at a natural, staggered pace
• Wave update — a left-to-right wave sweeps across all panels in a coordinated flip

Each character flip is animated mechanically: the top flap falls, then the new bottom flap rises, matching the physics of a real split-flap unit.

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Requirements

• macOS 12 or later
• Xcode 14+

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Build & Install

Using Make (recommended):

# Build and install to ~/Library/Screen Savers/
make install

# Build only (Release)
make build

# Build Debug
make debug

# Uninstall
make uninstall

Using Xcode:

1. Open SplitFlap.xcodeproj
2. Select the SplitFlap scheme
3. Build (⌘B)
4. Copy SplitFlap.saver from the build products to ~/Library/Screen Savers/

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Activate

1. Open System Settings → Screen Saver
2. Select SplitFlap from the list

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Project structure

File	Purpose
SplitFlapView.swift	Principal screensaver class, registered with macOS
CharacterGrid.swift	Manages the grid of individual panel cells
CharacterSet.swift	Defines the character alphabet and ordering
SplitFlapPanel.swift	Renders a single split-flap cell with CALayers
FlipAnimator.swift	Drives the mechanical flip animation via CABasicAnimation
DisplayClock.swift	Orchestrates idle and wave phases with a dispatch timer

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Part of OMT Global

A father-and-son open-source project.