Editor's note: this app is 100% organic, grass-fed vibecode

Marketing site: https://bpmtracker.app

BPM

Minimalist, distraction-free heart rate display for iPad and iPhone that connects to Bluetooth LE heart rate straps (GATT Heart Rate Service 0x180D). Built with SwiftUI and CoreBluetooth.

Repository Structure

This repository contains three main components:

• iOS App (BPM/): The SwiftUI iOS application for iPhone and iPad
• Static Marketing Site (backend/public/): Landing page and privacy policy hosted on Vercel
• Backend API (backend/pages/api/): Next.js API routes for heart rate sharing functionality

The marketing site and backend are deployed together on Vercel, with the static files served from backend/public/ and API routes at /api/*.

Features

• Live BPM: Large, high-contrast digits designed to be readable at a glance.
• HRV measurement: Guided two-minute RMSSD test powered by native RR intervals from straps like the Polar H10.
• BLE device discovery: Finds and connects to standard heart rate monitors.
• Quick device picker: Tap the antenna icon to select or switch devices.
• On-screen stats: Max and average over the last hour.
• Workout-friendly: Dark, high-contrast UI and idle timer disabled while active.
• Share your heart rate: Generate a share code and let friends view your live BPM remotely (requires an active subscription to start sharing; viewing others is free).
• View friend's heart rate: Enter a friend's code to see their live heart rate updates.

Requirements

• Xcode: 16 or newer.
• Devices: Universal (iPad and iPhone). UI optimized for portrait.
• iOS: Deployment target set to 17.0 (adjustable in project settings).
• Hardware: A real iPhone/iPad with Bluetooth LE (CoreBluetooth does not work in the simulator).
• Heart rate strap: Any BLE device that implements the Heart Rate Service (e.g., Polar H10, Wahoo TICKR, Garmin HRM, etc.). HRV measurements require a strap that streams RR intervals (Polar H10 or equivalent).
• IAP: Sharing requires a StoreKit 2 subscription product configured in App Store Connect (use BPM/Configuration.storekit for local testing).

Getting Started

1. Clone the repo:

   git clone https://github.com/<your-org-or-user>/BPM.git
   cd BPM

2. Open the project in Xcode:
   • Open BPM.xcodeproj.
   • Select your signing team if prompted (Targets → BPM → Signing & Capabilities).
3. Connect a real device and select it as the run destination.
4. Build & Run (Cmd+R).

Notes:

• App requires iOS 17.0 or later. If you need to support earlier iOS versions, lower the deployment target (Targets → BPM → General → iOS Deployment Target) to match your device, then rebuild.
• BLE requires a physical device; discovery/connection will not work in the simulator.
• App supports portrait orientation on both iPad and iPhone.

Permissions

The app requests Bluetooth access on first launch to scan and connect to your heart rate monitor.

• NSBluetoothAlwaysUsageDescription

You can change permission later in iOS Settings → Privacy & Security → Bluetooth → BPM.

Using the App

My Device Mode:

1. Put on and power your heart rate strap (so it starts advertising).
2. Launch the app (defaults to "My Device" mode).
3. Tap the antenna button to open the device picker and select your strap.
4. Your current BPM appears in large digits; Max and Avg (last hour) show at the bottom.
5. Optionally tap "Start Sharing" to generate a share code for friends to view your heart rate.

Friend's Code Mode:

1. Tap "Friend's Code" at the top of the screen.
2. Enter the 6-character share code provided by a friend.
3. View their live heart rate updates (updates every second).

HRV Measurement:

1. Connect a strap that streams RR intervals (Polar H10 or similar) in My Device mode.
2. From the main screen, tap the HRV button to open the measurement view.
3. Stay relaxed and still while the two-minute countdown runs (keep the app in the foreground).
4. When finished you'll hear haptic/audio feedback and see your RMSSD value along with session stats.

Project Structure

• BPMApp.swift: App entry; manages app lifecycle and scanning start/stop.
• ContentView.swift (HeartRateDisplayView): Main UI, BPM digits, stats bar, and sharing controls.
• DevicePickerView.swift: Scanning view and connect/disconnect actions.
• HeartRateBluetoothManager.swift: CoreBluetooth central, device discovery, connection, and HR parsing (8-bit and 16-bit per spec).
• HeartRateSample.swift: In-memory samples with timestamps for last-hour stats.
• SharingService.swift: API client for sharing heart rate data via backend service.
• Info.plist: Bluetooth usage descriptions and supported orientations (landscape).

Testing

• Unit and UI test targets are included.
• In Xcode: Product → Test (or Cmd+U).

Release (App Store Connect)

• Bump MARKETING_VERSION and CURRENT_PROJECT_VERSION in BPM.xcodeproj/project.pbxproj.
• Archive:
  • xcodebuild -project BPM.xcodeproj -scheme BPM -configuration Release -destination 'generic/platform=iOS' -archivePath build/BPM.xcarchive archive -allowProvisioningUpdates
• Export:
  • xcodebuild -exportArchive -archivePath build/BPM.xcarchive -exportPath build/export -exportOptionsPlist build/ExportOptions.plist -allowProvisioningUpdates
• Upload (API key):
  • Place key at ~/.appstoreconnect/private_keys/AuthKey_<KEYID>.p8
  • xcrun altool --upload-app -f build/export/BPM.ipa -t ios --apiKey <KEYID> --apiIssuer <ISSUER_ID>

Troubleshooting

• No devices found:
  • Ensure the strap is on your body (many devices only advertise when worn).
  • Move closer; BLE range is limited.
  • Toggle Bluetooth off/on, then rescan via the button.
  • Make sure the strap isn’t connected to another app/device.
• Permission denied: Go to iOS Settings → Privacy & Security → Bluetooth and allow access.
• Build fails due to iOS version: Lower the iOS Deployment Target in the target settings to match your device.

Sharing Setup

The app uses a backend service to share heart rate data. To enable sharing:

0. Subscription:

   • Sharing is gated by an in-app subscription; viewing other users' heart rates is free.
   • For local dev, attach BPM/Configuration.storekit to the scheme (Product -> Scheme -> Edit Scheme -> StoreKit Configuration).

1. Deploy the backend (see backend/README.md):

   • The backend is a Next.js app using Vercel KV (Upstash Redis).
   • Deploy to Vercel and set up environment variables (KV_REST_API_URL, KV_REST_API_TOKEN).
   • See backend/README.md for detailed setup instructions.

2. Configure the app:

   • Set the API base URL in the app by adding a UserDefaults key BPM_API_BASE_URL with your Vercel deployment URL.
   • Or modify SharingService.swift directly to change the default base URL.

3. Start sharing:

   • In "My Device" mode, tap "Start Sharing" to generate a 6-character code.
   • Share this code with friends who can enter it in "Friend's Code" mode.

Note: Heart rate updates are sent to the backend at 1 Hz (once per second) when sharing is enabled.

Privacy

• When sharing is disabled, no network calls are made; heart rate data stays on-device.
• When sharing is enabled, heart rate data is sent to your backend service (requires your own deployment).
• Samples are held in-memory and trimmed to the last hour.

Contributing

Issues and pull requests are welcome. For non-trivial changes, please open an issue first to discuss what you’d like to change.

Acknowledgements

• Bluetooth SIG GATT Heart Rate Service Specification (UUID 0x180D / 0x2A37).