HIIT Timer

A beautiful, elegant High-Intensity Interval Training timer for iOS 26+ with Liquid Glass design, Apple Music integration, and large touch-friendly controls optimized for workout use.

Features

• 5 Workout Modes: Intervals, Tabata (20/10), EMOM, AMRAP, Countdown
• Liquid Glass UI: iOS 26 Liquid Glass throughout with progressive blurs
• Apple Music Integration: Search and play workout music with album artwork behind the timer
• Large Buttons: Optimized for sweaty, tired fingers during workouts
• Multi-Sensory Feedback: Haptic patterns, audio cues, and phase color changes
• Floating Player: Mini music player in the tab bar accessory
• Presets: Save and reuse your favorite workouts
• Dark Mode: Always-dark interface for gym and low-light environments
• Background Audio: Timer runs in background with music

Workout Modes

Mode	Description	Default
Intervals	Alternating work/rest periods with configurable ratios	40s work/20s rest × 8
Tabata	Classic 20s work/10s rest × 8 rounds	Fixed protocol
EMOM	Every Minute on the Minute	12 minutes
AMRAP	As Many Rounds As Possible	10 minutes
Countdown	Simple countdown timer	5 minutes

Tech Stack

• Swift 6.3, SwiftUI, iOS 26+
• Liquid Glass (.glassEffect, GlassEffectContainer)
• MusicKit + ApplicationMusicPlayer
• CoreHaptics for haptic feedback
• AVFoundation for audio cues
• @Observable MV architecture

Build

# Build for iOS Simulator
swift build --sdk $(xcrun --show-sdk-path --sdk iphonesimulator) --triple arm64-apple-ios-simulator

# Or use Makefile
make build

Open in Xcode to run on simulator or device.

Project Structure

Sources/HIITTimer/
├── HIITTimerApp.swift          # App entry point
├── Models/
│   ├── WorkoutType.swift       # Interval, Tabata, EMOM, AMRAP, Countdown
│   ├── TimerPhase.swift        # Warmup, Work, Rest, Cooldown, Complete
│   ├── WorkoutPreset.swift     # Saved workout configurations
│   └── TimerEngine.swift       # Core timer @Observable engine
├── Services/
│   ├── HapticService.swift     # CoreHaptics feedback
│   ├── AudioFeedbackService.swift  # AVFoundation sounds
│   ├── MusicService.swift      # MusicKit / Apple Music
│   └── PresetStore.swift       # UserDefaults persistence
├── Views/
│   ├── ContentView.swift       # Tab view with floating player
│   ├── TimerView.swift         # Main workout timer
│   ├── PresetsView.swift       # Workout preset management
│   ├── MusicView.swift         # Music search and playback
│   └── Components/
│       ├── LargeCountdownDisplay.swift  # Full-screen countdown
│       ├── ControlButton.swift          # Large glass buttons
│       ├── AlbumArtBackground.swift     # Artwork behind timer
│       └── IntervalProgressBar.swift    # Visual progress

Setup

1. Enable MusicKit App Service in Apple Developer portal for your bundle ID
2. Add NSAppleMusicUsageDescription to Info.plist
3. Enable Background Audio capability for background playback