I was watching a YouTube prank where someone rigged it so Squidward footstep sounds played when they walked, or creaky joint noises played while they exercised — freaking people out. I watched it and thought "this would be fun as an app."
So I built it. Koforawalk.
How It Works
It analyzes accelerometer and gyroscope data from the Apple Watch to detect walking and running. When motion is detected, it plays pre-loaded sounds — Squidward footsteps, squeaks, shuffles, that kind of thing.
You can also record your own custom sounds. Make your own noises to mess with your friends. Real-time sync between iPhone and Apple Watch means you can use it on the watch alone or pair them together.
What Was Hard
Apple Watch development is surprisingly different. The architecture and constraints are nothing like regular iOS apps.
Distinguishing walking from running was tough. Accelerometer data alone wasn't enough, so I had to combine it with gyroscope data. Used the Core Motion framework to blend both sensor inputs. At first it was either way too sensitive or completely unresponsive. Went through multiple rounds of threshold tuning.
Latency was also an issue. Any delay between detecting motion and playing sound makes it feel completely off. The Apple Watch has limited battery and processing power, so the algorithm had to be efficient.
Used AVAudioPlayer for playback, AVAudioRecorder for recording, and the WatchConnectivity framework for iPhone-Watch sync.
Current State
It's on the App Store. Motion detection, footstep sounds, custom sound recording, iPhone-Watch sync — all working.
But honestly, the motion detection could be more precise, there should be more sound effects, and user settings need work. I can't say the polish is there yet. Still, the experience of actually building an Apple Watch app and getting it on the store was pretty valuable. Plan to keep improving it bit by bit.
Koforawalk is available for download on the App Store.