---
id: apis/Platform
title: Platform
officialDoc: https://reactnative.dev/docs/platform-specific-code
---

## `Platform.os`

React Native provides a module that detects the platform in which the app is
running. You can use the detection logic to implement platform-specific code.
Use this option when only small parts of a component are platform-specific.

```reason
if (Platform.os === Platform.ios) {
  // your code
}
```

`Platform.os` can be

- `Platform.ios` when running on iOS
- `Platform.android` when running on Android.
- `Platform.web` when running on the web (via
  [`react-native-web`](https://github.com/necolas/react-native-web)).

If you need an unsupported platform, you can use `Platform.unsafe(string)`.

For conditional style depending on the platform, you can do the following:

```reason
let styles =
  StyleSheet.create(
    Style.{
      "wrapper":
        style(
          ~width=pct(Platform.os == Platform.ios ? 100. : 200.),
          (),
        ),
    },
  );
```

## `Platform.select`

_⚠️ Unsupported._

This feature isn't relevant with ReasonML. Instead you can do the following:

```reason
let styles =
  StyleSheet.create(
    Style.{
      "wrapper":
        style(
          ~width=
            (
              switch (Platform.os) {
              | os when os == Platform.ios => 100.
              | os when os == Platform.android => 200.
              | os when os == Platform.web => 250.
              | os when os == Platform.unsafe("windows") => 300.
              | _ => 150.
              }
            )
            ->pct,
          (),
        ),
    },
  );
```

Also since spreading things in ReasonML is not supported (because of the
unsafety aspect), it's even less relevant to have this binding.