Detetcing IOS Device Temperature in Java

[SayyedaAsma]

Body

I am trying to detect iOS device temperature in Java. My project includes running the Appium server in Java to perform different actions on an iOS device. I am trying to use idevicesyslogs. From my research I know that iOS throws thermal state logs in syslogs when it sees a transition in states. These states include

1. Nominal: Normal operating temperature; no action needed.
2. Fair: Slightly elevated; system may start reducing resource-intensive operations.
3. Serious: High temperature; performance is significantly reduced (throttling CPU/GPU, lower frame rates).
4. Critical: Severely hot; device needs to cool down immediately, potentially disabling features or showing warnings before shutdown.

When transition between these states happens, only then can syslog capture thermal states. I have written this piece of code for my scenario. I have called the monitor device temperature in a thread that starts taking the logs when the Appium driver starts and continues until the device is connected to the Mac. Even when I change the device state by heating an iOS device, which triggers an alert for high temperature, the syslogs still fail to capture the thermal state. I have also tried:

1. ideviceinfo
2. idevicediagnostics
3. Long-running syslog capture
4. Running syslog manually in Terminal

None of these consistently expose the thermal state, even when the device shows overheating alerts. Also, The device was in developer mode.

` public String getIosThermalState() {
String syslogPath = DeviceComGlobals.LIBIMOBILEDEVICE_PATH + "/idevicesyslog";
String detectedState = "UNKNOWN";

    try {
        ProcessBuilder pb = new ProcessBuilder(syslogPath);
        Process process = pb.start();

        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        String line;

        // Read syslog for a short duration (1–2 seconds)
        long timeout = System.currentTimeMillis() + 1500;

        while (System.currentTimeMillis() < timeout && (line = reader.readLine()) != null) {
            String lower = line.toLowerCase();

            if (lower.contains("thermal") && lower.contains("state")) {
                if (lower.contains("nominal")) detectedState = "NOMINAL";
                if (lower.contains("fair")) detectedState = "FAIR";
                if (lower.contains("serious")) detectedState = "SERIOUS";
                if (lower.contains("critical")) detectedState = "CRITICAL";
                break;
            }
        }

        process.destroy();

    } catch (Exception e) {
        System.err.println("Error reading iOS thermal state: " + e.getMessage());
    }

    return detectedState;
}

public void monitorDeviceTemperature() {
    String baseMessage = "Playback in Progress, training scenario id: %s";
    String message;

    try {
            // *********** IOS THERMAL STATE ************
            System.out.println("Started checking Thermal State for Ios devices");
            String state = getIosThermalState();
            switch (state) {
                case "NOMINAL":
                    message = "Normal Temperature (Nominal Thermal State)"+ baseMessage;
                    break;
                case "FAIR":
                    message ="Warning! Abnormal Device Temperature (Fair Thermal State)"+ baseMessage;
                    break;
                case "SERIOUS":
                    message = "Warning! Serious Thermal State Detected: Performance Throttling May Occur"+ baseMessage;
                    break;
                case "CRITICAL":
                    message = "Device Overheating! Critical Thermal State"+ baseMessage;
                    break;
                default:
                    message = "Unable to fetch device temperature (Thermal State Unknown)"+ baseMessage;
            }
        System.out.println(message);

    } catch (Exception e) {
        System.err.println("Error monitoring device temperature/thermal state: " + e.getMessage());
        e.printStackTrace();
    }
}`

Question

Is there any supported or reliable way to detect iOS thermal state externally (from Java/Appium/libimobiledevice) without modifying the application under test?

Or is syslog-based detection fundamentally unreliable by design due to Apple’s platform restrictions?

Any confirmation or alternative approaches from the community would be appreciated.

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