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Mechanical split-flap displays — the ones that clatter through the alphabet in old train stations — rendered in SwiftUI. Tiles flip, rows spell themselves out left to right, and nothing depends on anything but SwiftUI.

What's in it

SplitFlapRow	a line of tiles that flips when the text changes
SplitFlapTile	one tile, if you want to build your own layout
SplitFlapStaticRow	the same look in a single Canvas pass, for rows that never change
SplitFlapTheme	two colours, plus four bundled

Installation

Add the package in Xcode via File → Add Package Dependencies, or in Package.swift:

dependencies: [
    .package(url: "https://github.com/Staberman/splitflap.git", from: "1.0.0")
]

Usage

A row of text

import SplitFlap

SplitFlapRow(text: "BUENOS AIRES", theme: .classic, columns: 14)

Change text and the tiles flip to the new value, each column a beat after the one before. Text is upper-cased, cut to columns, and padded with blanks — so a row is always the same width, whatever it says.

A single tile

SplitFlapTile(value: "7", theme: .classic)
    .frame(width: 44, height: 60)

The tile fills whatever frame you hand it, and scales its type to match.

Spelling itself out on appear

SplitFlapRow(
    text: "DEPARTURES",
    theme: .midnight,
    columns: 10,
    cascadesOnAppear: true
)

Stagger several rows with cascadeDelay and a board spells itself line by line.

Sound and haptics

The package makes no noise of its own. onFlip fires on the main actor each time a row changes, and what happens next is yours:

SplitFlapRow(text: gate, theme: .classic, columns: 4) {
    playClack()  // your sound, your haptic, or nothing — the package has no opinion
}

Themes

Four are bundled — .classic, .daylight, .midnight, .retro — and a theme is just two colours, so your own is one line:

let terminal = SplitFlapTheme(
    id: "terminal",
    card: Color(white: 0.08),
    digit: .green
)

Performance

A board is a lot of layers. Every tile draws two clipped halves, two rotated halves while it flips, a shadow and a stroke — and SwiftUI walks all of them on every frame, for every tile, even the ones that never change.

On a large board most rows never change: filler lines, closed rows, values restored from disk. SplitFlapStaticRow draws one of those in a single Canvas pass — one layer instead of dozens:

SplitFlapStaticRow(text: "— — — — —", theme: .classic, columns: 5)

It is pixel-identical to a row of resting tiles. Use it for anything that will not flip, and keep SplitFlapRow for what will. On the board this package came from, that single swap cut re-rendered layers per frame by about 92%.

Accessibility

• Reduce Motion is honoured: tiles change value without animating, and rows skip their cascade.
• A row is one accessibility element labelled with its full text — VoiceOver reads BUENOS AIRES, not fourteen separate letters.

Requirements

iOS 17 · macOS 14 · tvOS 17 · visionOS 1 · Swift 5.9

Credits

Extracted from Pomotti, a split-flap focus timer for iPhone, iPad and Mac.

License

MIT — see LICENSE. Use it, ship it, no attribution required.