# Mobile

## Supported Platforms: Web, iOS, Android

By default, your Activity will be launchable on web/desktop. To enable or disable support for Web/iOS/Android, do the following:

- Visit the [developer portal](https://discord.com/developers/applications)
- Select your application
- Select [Activities -> Settings](https://discord.com/developers/applications/select/embedded/settings) in the left-side of the developer portal
- From check the appropriate checkboxes in the developer portal, and save your changes

![supported-platforms](../img/images/activities/supported-platforms.png)

***

## Mobile Safe Areas

As an example, you can define your safe area insets as below in CSS:

```css
:root {
  --sait: var(--discord-safe-area-inset-top, env(safe-area-inset-top));
  --saib: var(--discord-safe-area-inset-bottom, env(safe-area-inset-bottom));
  --sail: var(--discord-safe-area-inset-left, env(safe-area-inset-left));
  --sair: var(--discord-safe-area-inset-right, env(safe-area-inset-right));
}
```

This prefers the `--discord-safe-area-inset-*` variable and will fallback to the env values for iOS + any local dev testing that is done outside of Discord.

You can then reference these values:

```css
body {
  padding-left: var(--sail);
  padding-right: var(--sair);
  padding-top: var(--sait);
  padding-bottom: var(--saib);
}
```

***

## Mobile Thermal States

You may need to respond to thermal state changes using recommendations from [thermal states surfaced by mobile devices](https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/RespondToThermalStateChanges.html) to improve the user experience.

Discord's Embedded App SDK provides an abstraction over [Apple's thermal state APIs](https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/RespondToThermalStateChanges.html) and [Android's thermal state APIs](https://source.android.com/docs/core/power/thermal-mitigation#thermal-api).

Here's how Discord's abstraction maps to Apple's thermal states and Android's thermal states.

```javascript
enum ThermalState {
  NOMINAL = 0, // maps to "nominal" on iOS and "none" on Android
  FAIR = 1, // maps to "fair" on iOS and "light" / "moderate" on Android
  SERIOUS = 2, // maps to "serious" on iOS and "severe" on Android
  CRITICAL = 3, // maps to "critical" on iOS and "critical" / "emergency" / "shutdown" on Android
}
```

The Embedded App SDK allows developers to subscribe to these thermal state changes.

```javascript
const handleThermalStateUpdate = (update: {thermal_state: number}) => {
  switch (thermalState) {
      case Common.ThermalStateTypeObject.NOMINAL:
        ...
      case Common.ThermalStateTypeObject.FAIR:
        ...
      case Common.ThermalStateTypeObject.SERIOUS:
        ...
      case Common.ThermalStateTypeObject.CRITICAL:
        ...
      default:
        ...
    }
}

discordSdk.subscribe('THERMAL_STATE_UPDATE', handleThermalStateUpdate);
```

Discord will publish the current thermal state upon event subscription, and it will also publish any thermal state changes that happen afterward.

:::callout{intent="info"}
On Android devices, the thermal state updates will only be available on Android 10 and higher.
:::

## Related pages

- [API Reference](./api-reference-index.md)
- [App Fundamentals](./app-fundamentals-index.md)
- [Best Practices](./best-practices-index.md)
- [Bots & Companion Apps](./bots-companion-apps-index.md)
- [Building Games](./building-games-index.md)
- [Building on Discord](./building-on-discord-index.md)
- [Change Log](./change-log-index.md)
- [Communities & Servers](./communities-servers-index.md)
- [Components](./components-index.md)
- [Core Concepts](./core-concepts-index.md)

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