HRV Breathe

The brief

Breathing apps abound, but most skip the science. They guide inhale-exhale without measuring whether the practice actually changes your physiology. HRV — heart rate variability — is the gold standard for stress resilience, yet no breathing app reads pre/post HRV from HealthKit to show measurable impact.

Design and build a native iOS & watchOS app that pairs a signature lava lamp animation with real HRV data. Six breathing patterns, automatic HealthKit sync, streaks, goals, stats, and an Apple Watch companion — all shipped from zero to App Store.

Session setup & pacer

Six breathing patterns split into two families — three resonance-frequency patterns (4-6, 5-5, 6-4 inhale-exhale splits) for HRV optimization, and three classic techniques (Box Breathing, 4-7-8, Relaxing Breath) for acute calm. Choose your pattern, set a duration — 3, 5, or 10 minutes — and begin.

The pacer is the lava lamp blob itself: nine overlapping circles with teal/cyan gradients that expand on inhale, contract on exhale, and hold mid-breath during retention phases. A floating particle system, phase text, and a progress arc complete the immersive full-screen experience. Haptic pulses mark phase transitions.

Session complete

Every session ends with a summary: total time, pattern used, and — the key differentiator — a pre/post HRV comparison card. HealthKit reads HRV samples before and after the session, calculates the delta, and displays the result as a clear ‘+8 ms’ improvement badge.

Streak motivation appears inline: current streak count, best streak, and a nudge to keep the chain going. Save the session and it flows into the stats dashboard automatically.

Stats dashboard

The dashboard is command central: a goal ring tracking weekly session targets, a streak card with flame icon, weekly session count, and an HRV trend sparkline built with Swift Charts. All data persisted in SwiftData with automatic CloudKit sync.

The design uses glassmorphism throughout — translucent cards with subtle blur over the dark background, teal accent highlights on interactive elements, and smooth spring animations on every state change.

HRV insights

A multi-layer chart built with Swift Charts shows the full picture: daily HRV readings as vertical bars with min/max bands, a 7-day rolling average trend line, and practice session markers overlaid to correlate breathing practice with HRV improvement over time.

The visualization answers the question every user asks: ‘Is this actually working?’ By combining HealthKit HRV data with session history, the chart reveals patterns that individual sessions can’t show.

Apple Watch companion

Standalone watchOS 10+ app with a simplified blob animation, session setup via Digital Crown, and haptic-only guidance — no need to look at the screen. WatchConnectivity syncs session data bidirectionally between iPhone and Watch.

The Watch app supports all six breathing patterns with haptic phase transitions tuned to each pattern’s timing. Start a session from the Watch, finish it, and see it reflected on your iPhone dashboard instantly.

HRV education

Four interactive slides explain HRV to newcomers — what it is, why it matters, how breathing affects it, and how to interpret your data. Animated heartbeat waveforms and breathing demo animations make abstract concepts tangible.

Accessible from settings and surfaced on first launch. The goal: ensure every user understands why they’re breathing with intention, not just following a circle.

Settings & audio

Ambient sound picker with four nature soundscapes — rain, ocean, forest, and white noise — layered under breathing guidance via AVFoundation audio mixing. Haptic intensity slider from subtle to strong with CoreHaptics custom patterns. Light/dark appearance toggle with system-default option.

Every preference persists in SwiftData and syncs to the Watch via WatchConnectivity. The settings surface is designed to be discovered once and forgotten — sensible defaults mean most users never need to visit.

Technical details

100% native SwiftUI with zero third-party dependencies. SwiftData for persistence with CloudKit sync. HealthKit integration for HRV reads with background observer queries. AVFoundation for ambient audio mixing, CoreHaptics for custom haptic patterns across 6 breathing rhythms.

watchOS 10+ companion with WatchConnectivity bidirectional sync. Swift Charts for HRV visualization and stats dashboard. Three-tier persistence: SwiftData (structured), UserDefaults (preferences), HealthKit (read-only). 63 Swift files, 85 unit tests, full Dynamic Type and VoiceOver accessibility.

Results

Shipped from concept to App Store — iOS 17+ and watchOS 10+ — with product strategy, UX/UI design, and full SwiftUI development handled in-house. 63 Swift files, 85 tests, 6 breathing patterns, Apple Watch companion, and the only breathing app that reads your actual HRV data to prove it’s working.

The same SUUR approach: understand the science, design the experience, ship with purpose.