An iOS + watchOS companion app that monitors device (iPhone) and AirPods orientation in real-time, calculates how far "down" your head is, and provides audio saying “look up” if your head dips below a certain threshold. The watch app displays the calibration status and allows you to toggle muting, calibrate, or re-calibrate with a simple "slide to confirm" gesture.
Additionally, the phone’s orientation is used to account for slope angle. By storing the phone on your upper body (e.g., a chest pocket), the app can determine a reference angle between the chest and head, allowing it to function reliably across different slope inclines.
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Real-Time Head Tracking
- Uses
CMMotionManagerto track the iPhone’s orientation (pitch, roll, yaw). - Uses
CMHeadphoneMotionManager(when available on compatible AirPods) to track the user’s head orientation. - Phone orientation aids slope reference: The phone, placed on your upper body, helps derive a consistent baseline angle even on varying slopes.
- Uses
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Calibration
- Quick, two-step calibration:
- Capture a neutral “heads-up” position.
- Capture a “head-down” position.
- Once calibrated, the app calculates a percentage of how “down” your head is based on these two reference points.
- Quick, two-step calibration:
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Audio Alerts
- Plays audio saying “look up” (from
look_up.wav) whenever your head is too far down. - You can toggle muting if you don’t want to hear the audio message.
- Plays audio saying “look up” (from
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Prevents App Suspension
- The app plays a very quiet, looping one-second silent MP3 in the background to keep the audio session active, reducing the likelihood of iOS suspending the app while it’s in the background (e.g., while skiing).
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watchOS Companion
- Displays calibration state (“Not Started”, “Neutral Head”, “Head Down”, “Calibrated”).
- Allows you to slide to calibrate or re-calibrate.
- A toggle lets you mute/unmute the audio from your wrist.
Below are the primary Swift files and their roles:
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MotionViewModel.swift- Orchestrates iPhone and AirPods motion data collection.
- Manages calibration states, threshold detection, and audio logic.
- Maintains a reference to a
SilentAudioManagerthat keeps the app’s audio session alive in the background.
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WatchConnectivityManager.swift- Bridges data between the iOS app and the watchOS app using
WCSession. - Sends calibration stage and mute state to the Watch; receives watch “actions” (calibrate, re-calibrate, set mute).
- Bridges data between the iOS app and the watchOS app using
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ski_coachApp.swift- The main entry point for the iOS app.
- Configures the audio session and starts silent audio playback through
SilentAudioManager. - Initializes
MotionViewModelandWatchConnectivityManagerto share data.
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ContentView.swift(iOS)- A simple SwiftUI view that shows iPhone pitch/roll/yaw, AirPods pitch/roll/yaw, and calibration status.
- Starts and stops motion updates appropriately when appearing/disappearing.
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MyWatchApp.swift/watch_ski_coachApp.swift- The main entry point for the watchOS app.
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WatchSessionManager.swift- The watchOS counterpart to
WatchConnectivityManager.swift. - Receives calibration stage and mute state from iOS, and sends user actions (calibrate, re-calibrate, set mute) back to iOS.
- The watchOS counterpart to
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ContentView.swift(watchOS)- Shows calibration stage and includes UI for “slide to calibrate” or “slide to re-calibrate,” plus a toggle for mute.