Better Keyboard

A custom iOS keyboard with swipe-to-type, featuring a unique circular ring layout alongside traditional grid layouts (QWERTY, Dvorak, Workman, and a custom "Coyote" layout).

Layouts

Ring — A dual-ring circular layout where 26 letters are arranged around two concentric rings. Key placement was optimized via simulated annealing to maximize distance between common bigrams, making swipe paths more distinct and accurate. High-frequency letters (E, T, A, O, I, N, S, H) sit on the inner ring for quick thumb reach.

QWERTY / Dvorak / Workman — Standard grid layouts with ortholinear key positioning (no row stagger). Swipe-to-type works on all of them.

Coyote — A custom vertical-cluster layout designed for phone typing. The 9 most common letters are grouped in the center columns so common bigrams (HE, IN, ST) become vertical thumb movements rather than horizontal reaches.

Users cycle between all five layouts with a keyboard button. Last-used layout persists across sessions.

Features

• Swipe-to-type with dictionary matching and word predictions
• Tap typing on all layouts
• Smart spacing — words are auto-spaced after swipes; opening quotes/brackets suppress the leading space, closing quotes/brackets eat the trailing space
• Smart punctuation — period, comma, and other punctuation auto-delete the preceding space; double-space inserts ". "
• Smart contractions — ambiguous swipes (e.g., "dont") auto-insert the apostrophe ("don't"); tap-apostrophe toggles between contraction and plain word
• Auto-shift after sentence-ending punctuation
• Auto-correct (standalone "i" → "I")
• Swipe gestures on special keys — swipe left from backspace to erase a whole word; swipe right from space to jump cursor to end of text
• Symbol mode — two sets of symbols/numbers
• Cursor mode (ring layout) — hold center, drag to move cursor

Project Structure

optimizer/          Python simulated annealing for ring letter placement
BetterKeyboard/
  project.yml       XcodeGen project definition
  BetterKeyboardApp/    Container app (enable-keyboard instructions)
  KeyboardExtension/    The keyboard
    Layout/         Key positions, layout protocols, geometry
    Rendering/      Ring + grid views, key cap layers, swipe trail
    Input/          Touch routing, swipe tracking, word decoding
    Dictionary/     Word list + frequency-indexed lookup

Building

Requires Xcode and XcodeGen.

brew install xcodegen    # if not already installed
cd BetterKeyboard
xcodegen generate
open BetterKeyboard.xcodeproj

Build the BetterKeyboardApp scheme, then enable the keyboard in Settings → General → Keyboard → Keyboards → Add New Keyboard.

How It Works

Swipe Decoding

Swipe decoding happens in two stages:

Tracking (SwipeTracker): During a swipe, every touch sample is recorded with its timestamp. On finger lift, the full path is analyzed using velocity — the finger naturally slows down over intended letters (velocity minima) and speeds up between them. These dwell points become high-weight "anchor" keys, while letters the finger merely passes near get low weight. Endpoints (start/end of swipe) are always anchors. Loop gestures over a key are detected separately for double letters (e.g., "ll").

Matching (SwipeDecoder): The weighted key sequence is matched against a ~50k word dictionary. Candidates are looked up by first/last letter, then scored with alignment: word letters are greedily matched to the key sequence in order, with two tiers of miss penalty (letters that exist in the sequence but couldn't match in order vs. letters completely absent from the path). Scoring also factors in anchor weight alignment, key sequence coverage, word length, frequency rank, and unsupported double-letter detection. The top N matches feed the prediction bar.

Ring Geometry

The ring uses normalized polar coordinates converted to screen positions at layout time. Two 36° gaps at 0° (space) and 180° (backspace) divide the ring into upper and lower arcs. Keys occupy wedge-shaped hit regions with inner/outer radial boundaries.

Grid Geometry

Grid layouts compute key positions from view width — keys are evenly sized, shorter rows are centered, and all columns align vertically (ortholinear). The swipe pipeline is shared between ring and grid; only the proximity threshold differs (26pt ring, 20pt grid).

Optimizer

The optimizer/ directory contains a Python simulated annealing optimizer that finds letter placements for the ring layout. It maximizes weighted bigram distances so common letter pairs (TH, HE, IN, etc.) are far apart on the ring, reducing swipe ambiguity.

cd optimizer
python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
python run.py

License

This project is not currently licensed for reuse. All rights reserved.