MorseModem

A SwiftUI iOS / iPadOS app that encodes text to Morse code audio and decodes Morse audio back to text. On-device, no network, no third-party dependencies.

Features

• Encoder — text → Morse audio. Sine-wave tone with 5 ms fade in/out, parallel haptic pattern (lighter for dots, stronger for dashes), export to AAC .m4a.
• Decoder — record from the microphone or import an audio file (Files app, AirDrop, "Open in MorseModem" share sheet). Live RMS waveform; auto-detects the sender's WPM from the shortest tone.
• Reference — searchable table of letters, numbers, and punctuation; tap a row to hear it.
• History — every encoded/decoded message persists via SwiftData; searchable and copyable.

Settings: tone frequency, words-per-minute (PARIS timing), volume.

More information about the app: https://morsemodem.lhomme.xyz/

Requirements

• iOS / iPadOS 26.4 minimum (both MorseModem and MorseModem Beta schemes)
• Also runs on macOS (Designed for iPad) and visionOS (Apple Vision Pro) via the iPad build
• Xcode supporting Swift 6 strict concurrency
• Microphone permission (recording) and Files access (audio import) — requested at first use

Building

# 1. Configure your team
cp Config.xcconfig.template Config.xcconfig
# edit DEVELOPMENT_TEAM = <your team id>

# 2. Build for simulator
xcodebuild -project MorseModem.xcodeproj -scheme MorseModem -configuration Debug \
  -destination 'platform=iOS Simulator,name=iPhone 16' build

# 3. Run unit tests
xcodebuild -project MorseModem.xcodeproj -scheme MorseModem \
  -destination 'platform=iOS Simulator,name=iPhone 16' test

Config.xcconfig is gitignored. Simulator builds work without a team id.

Schemes:

Scheme	Configuration	Bundle id
MorseModem	Debug/Release	xyz.nlhomme.MorseModem
MorseModem Beta	Beta	xyz.nlhomme.MorseModem.beta

Tech

• SwiftUI + @Observable view models, MVVM, @MainActor-bound app
• SwiftData for Message history and AppSettings
• AVFoundation (AVAudioEngine, AVAudioPlayerNode) for tone synthesis and capture
• CoreHaptics for synchronized tactile feedback
• Swift Testing (@Suite/@Test/#expect) for unit tests; XCTest for UI tests

All processing runs on-device. No analytics, no network calls.

Project layout

Sources are flat under MorseModem/ — no on-disk subgroups for Models / Services / Views.

MorseModem/             // App sources (Swift, Assets, Localizable.xcstrings, Info.plist)
MorseModemTests/        // Swift Testing unit tests
MorseModemUITests/      // XCTest UI tests
docs/                   // Architecture + implementation docs
assets/                 // App icon source SVGs and screenshots
Config.xcconfig.template

For the why behind the code (audio pipeline, decoder thresholds, share-sheet plumbing, Swift 6 concurrency notes), see:

• docs/ARCHITECTURE.md
• docs/IMPLEMENTATION_GUIDE.md
• CLAUDE.md — orientation notes for working in this repo

Accessibility

VoiceOver labels on all controls, AccessibilityNotification.Announcement calls around recording state changes, Dynamic Type, light/dark modes. Haptics provide non-audio feedback during encoder playback.

License

Licensed under the PolyForm Noncommercial License 1.0.0 — free to use, modify, and redistribute for any noncommercial purpose. Commercial use is not permitted; for a commercial license, contact the author.

Copyright © 2026 Nicolas Lhomme.