TemperatureIcon

Minimal native macOS menu bar app that shows the current Apple Silicon CPU/SoC temperature.

The Xcode project is named TemperatureIcon; the installed app appears as CPU Temperature.

Current menu bar format:

CPU 45°C

Screenshot

The screenshot is a cropped strip of the macOS menu bar. The app does not open a main window.

Compatibility

• macOS 14 or later.
• Apple Silicon Mac.
• Tested locally on a MacBook Air Apple Silicon where macOS exposed PMU tdie* and PMU2 tdie* sensors.
• Not intentionally limited to M4. The HID/IOKit method may work on other Apple Silicon M-series chips, but it is not guaranteed on every model.
• Intel Macs are not supported in the current implementation.

Limitations

Apple does not provide a public stable API for reading Apple Silicon CPU/SoC temperature in Celsius. TemperatureIcon uses undocumented HID/IOKit sensor paths.

That means:

• Sensor names can change between M1, M2, M3, M4, and future generations.
• The app displays a representative die/SoC reading, not an official per-core temperature.
• It may stop working if Apple changes sensor access or permissions in a future macOS release.
• App Sandbox is disabled because HID/IOKit sensor reading may fail inside the sandbox.

Project Structure

TemperatureIcon/TemperatureIcon/
  App/
    TemperatureIconApp.swift
  Monitoring/
    TemperatureMonitor.swift
  Sensors/
    TemperatureReader.swift
    SensorBridge.c
    SensorBridge.h
    TemperatureIcon-Bridging-Header.h
  Views/
    ContentView.swift
  Assets.xcassets/
Sources/
  SensorBridge/
  temperature-cli/

Main Components

• TemperatureIcon/TemperatureIcon/App/TemperatureIconApp.swift: app entry point and MenuBarExtra.
• TemperatureIcon/TemperatureIcon/Monitoring/TemperatureMonitor.swift: current reading, 5-second timer, and menu bar formatting.
• TemperatureIcon/TemperatureIcon/Sensors/TemperatureReader.swift: chooses the CPU/SoC sensor reading.
• TemperatureIcon/TemperatureIcon/Sensors/SensorBridge.c: low-level HID/IOKit sensor access.
• Sources/temperature-cli: minimal CLI prototype used to validate sensor access before building the SwiftUI app.

Run the App

Open:

TemperatureIcon/TemperatureIcon.xcodeproj

Select the TemperatureIcon scheme and press Run.

The app uses LSUIElement, so it appears only in the menu bar and not in the Dock.

CLI Prototype

Build:

swift build

List detected temperature sensors:

.build/debug/temperature-cli --list

Print the selected CPU/SoC reading:

.build/debug/temperature-cli

Privacy and Security

Local review before sharing:

• No network requests.
• No URLSession, sockets, or HTTP APIs.
• No external command execution.
• No access to user documents.
• No Keychain usage.
• No tokens, secrets, or credentials.
• Only reads temperature sensors via HID/IOKit and updates menu bar text.

References

• Stats documents that Apple Silicon CPU/GPU sensors are thermal zones and that Apple changes sensor keys between SoCs.
• mactop uses IOKit / IOHIDEventSystemClient for Apple Silicon monitoring.
• apple_sensors write-up explains the HID approach for reading temperatures on M-series Macs.

License

MIT 🗿