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# ProcessInfo.ThermalState

Values used to indicate the system’s thermal state.

```
enum ThermalState
```

## Overview

These values are used by the [`ProcessInfo`](/documentation/Foundation/ProcessInfo) class as return values for [`thermalState`](/documentation/Foundation/ProcessInfo/thermalState-swift.property).

For information about testing your app under different thermal states, see [Test under adverse device conditions](https://help.apple.com/xcode/mac/current/#/dev308429d42).

## Topics

### Enumeration Cases

### Constants

[`ProcessInfo.ThermalState.nominal`](/documentation/Foundation/ProcessInfo/ThermalState-swift.enum/nominal)

The thermal state is within normal limits.

[`ProcessInfo.ThermalState.fair`](/documentation/Foundation/ProcessInfo/ThermalState-swift.enum/fair)

The thermal state is slightly elevated.

[`ProcessInfo.ThermalState.serious`](/documentation/Foundation/ProcessInfo/ThermalState-swift.enum/serious)

The thermal state is high.

[`ProcessInfo.ThermalState.critical`](/documentation/Foundation/ProcessInfo/ThermalState-swift.enum/critical)

The thermal state is significantly impacting the performance of the system and the device needs to cool down.


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