Your iPhone's sensors, as clear live readings — and what each one actually measures.
 Readings |
 Attitude, in 3D |
 Chart and stats |
 Compass |
 Sound meter |
Simulator captures: every number in them comes from a synthetic source.
- 19 live readings across motion, environment, location and the device itself — each with a chart, min/max/average, a plain-English explainer and everyday comparisons ("60 dB is a conversation; 85 dB is heavy traffic").
- Five instruments — Attitude (your phone in 3D, turning as it does), a spirit level, a compass, a sound meter and a light meter.
- Recording — log any readings at 1, 10 or 50 Hz, watch them as they run, see the route a journey took, and export CSV. A recording that logs your position carries on in your pocket.
- Calibration against a reference sound or lux meter, if you own one.
- True black by default, seven themes and an interface size; every animation respects Reduce Motion.
Everything it reads
| Group | Readings |
|---|---|
| Motion | Acceleration, rotation rate, orientation, magnetic field, heading |
| Environment | Air pressure, relative altitude, sound level, light |
| Location | Coordinates, GPS altitude, speed, course, accuracy |
| Device & activity | Steps/distance/floors, cadence and pace, proximity, battery, thermal state |
iOS exposes neither the ambient light sensor nor air temperature. Light is estimated from the camera's exposure, so it carries a "≈"; "Phone heat" is the device's own thermal state, not the room's.
No ads, no accounts, no analytics. Everything is measured and stored on the phone, and Readout makes no network request of its own — the one optional exception, showing a recorded route on Apple Maps, is off until you turn it on. Microphone audio and camera frames are read in memory for a level and never saved. Each permission is asked for only when a reading needs it.
You need Xcode 26 or later, and an iPhone on iOS 26 or the Simulator. There are no dependencies to install.
git clone https://github.com/leeyenkai/Readout.git
open Readout/Readout.xcodeproj- Simulator — runs as it is. There are no sensors there, so every reading comes from a synthetic source and says "Simulated".
- Your iPhone — signing is deliberately unset: choose your team under Signing &
Capabilities. A free Apple ID works for seven days at a time. The full sequence is in
docs/RELEASE.md§2.
Run the tests from the command line, with any simulator from
xcrun simctl list devices available:
xcodebuild -project Readout.xcodeproj -scheme Readout \
-destination 'platform=iOS Simulator,name=iPhone 17' testv0.6.0. Everything above is built and tested in the Simulator, and CI builds and tests
every push. It has not yet been verified on a physical iPhone — the on-device checklist that
gates 1.0 is in docs/RELEASE.md §3. There is no plan to put it on the
App Store; it is made to be built and shared.
- Changelog — what each release changed
- Specification — scope and requirement IDs, the source of truth
- Running and sharing it — signing it for your own iPhone, passing it on, and the on-device checklist that gates 1.0
- Contributing — how to propose and make a change
- Working agreement — architecture, conventions and privacy rules
Free and open source under the MIT licence — use it, change it and share it.