> For the complete documentation index, see [llms.txt](https://developers-apps-in-toss.toss.im/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers-apps-in-toss.toss.im/documentation/api-and-sdk-en/react-native/screen-navigation/layout.md).

# Layout

Layout is a structure for consistently managing UI elements that repeat across multiple pages (headers, navigation bars, footers, etc.). By defining a common layout, you can reduce code duplication and provide a consistent user experience.

### Creating a layout file

The layout is `_layout.tsx` It is defined by creating a file. The scope it applies to depends on the file's location.

```tsx
import { PropsWithChildren } from "react";

export default function Layout({ children }: PropsWithChildren) {
  return <>{children}</>;
}
```

### Setting the layout scope

Layouts are applied automatically based on the file path.

* `pages/_layout.tsx`: Applied globally to all pages.
* `pages/about/_layout.tsx`: `intoss://{serviceName}/about` Applied only to all pages beneath it.

Layouts can be nested. When multiple layouts are present together, they are applied in order, starting from the layout in the parent directory.

```
pages/
├── _layout.tsx          // Global layout
├── about/
│   ├── _layout.tsx     // about section layout
│   ├── index.tsx       // about main page
│   └── team.tsx        // team introduction page
└── index.tsx           // main page
```

For example, if the structure is as above `about/team.tsx` the page's layout is applied in the following order.

1. `pages/_layout.tsx` (Global layout)
2. `pages/about/_layout.tsx` (Section layout)
3. `pages/about/team.tsx` (Actual page component)

With this structure, you can separately manage UI elements needed globally and UI elements needed only in specific sections.

### Layout example

#### Global layout

Let's create a layout that applies commonly to all pages.

{% tabs %}
{% tab title="pages/\_layout.tsx" %}

```tsx
import { PropsWithChildren } from "react";
import { View } from "react-native";
import { Header } from "../components/Header";
import { Footer } from "../components/Footer";

export default function Layout({ children }: PropsWithChildren) {
  return (
    <View style={{ flex: 1 }}>
      <Header />
      {children}
      <Footer />
    </View>
  );
}
```

{% endtab %}

{% tab title="components/Header.tsx" %}

```tsx
import { View, Text, StyleSheet } from "react-native";

export function Header() {
  return (
    <View style={styles.header}>
      <Text style={styles.title}>My App</Text>
      <View style={styles.nav}>
        <Text style={styles.navItem}>Home</Text>
        <Text style={styles.navItem}>About</Text>
        <Text style={styles.navItem}>Settings</Text>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  header: {
    padding: 16,
    backgroundColor: "#ffffff",
    borderBottomWidth: 1,
    borderBottomColor: "#e5e5e5",
  },
  title: {
    fontSize: 24,
    fontWeight: "bold",
    marginBottom: 8,
  },
  nav: {
    flexDirection: "row",
    gap: 16,
  },
  navItem: {
    fontSize: 16,
    color: "#666666",
  },
});
```

{% endtab %}

{% tab title="components/Footer.tsx" %}

```tsx
import { View, Text, StyleSheet } from "react-native";

export function Footer() {
  return (
    <View style={styles.footer}>
      <Text style={styles.copyright}>© 2024 My App. All rights reserved.</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  footer: {
    padding: 16,
    backgroundColor: "#f5f5f5",
    alignItems: "center",
  },
  copyright: {
    fontSize: 14,
    color: "#666666",
  },
});
```

{% endtab %}
{% endtabs %}

#### Section-specific layout

You can create layouts used only in specific sections.

{% tabs %}
{% tab title="pages/about/\_layout.tsx" %}

```tsx
import { PropsWithChildren } from "react";
import { View } from "react-native";
import { AboutSidebar } from "../../components/AboutSidebar";

export default function AboutLayout({ children }: PropsWithChildren) {
  return (
    <View style={{ flexDirection: "row" }}>
      <AboutSidebar />
      <View style={{ flex: 1 }}>{children}</View>
    </View>
  );
}
```

{% endtab %}

{% tab title="components/AboutSidebar.tsx" %}

```tsx
import { View, Text, StyleSheet } from "react-native";

export function AboutSidebar() {
  return (
    <View style={styles.sidebar}>
      <Text style={styles.title}>About</Text>
      <View style={styles.menu}>
        <Text style={styles.menuItem}>Company Overview</Text>
        <Text style={styles.menuItem}>Team Introduction</Text>
        <Text style={styles.menuItem}>History</Text>
        <Text style={styles.menuItem}>Directions</Text>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  sidebar: {
    width: 200,
    padding: 16,
    backgroundColor: "#f8f9fa",
    borderRightWidth: 1,
    borderRightColor: "#e5e5e5",
  },
  title: {
    fontSize: 20,
    fontWeight: "bold",
    marginBottom: 16,
  },
  menu: {
    gap: 12,
  },
  menuItem: {
    fontSize: 16,
    color: "#495057",
  },
});
```

{% endtab %}
{% endtabs %}

### Getting query parameters in a layout

You can also use query parameters in a layout. `useParams` Using the hook, you can read the current screen's parameters and use them dynamically.

#### `useParams` Hook usage example

In the example below, the `title` value passed as a URL query parameter is retrieved and displayed as the top title of the screen.

{% tabs %}
{% tab title="pages/\_layout.tsx" %}

```tsx
import { useParams } from "@granite-js/react-native";
import { PropsWithChildren } from "react";
import { View, Text } from "react-native";

export default function Layout({ children }: PropsWithChildren) {
  // Get the current screen's parameters.
  const params = useParams({ strict: false });

  // Get the 'title' parameter and set a default value.
  const title = params?.title ?? "Default Title";

  return (
    <View style={{ flex: 1 }}>
      {/* Dynamically generated header */}
      <View style={{ padding: 16, backgroundColor: "#f0f0f0" }}>
        <Text style={{ fontSize: 20, fontWeight: "bold" }}>{title}</Text>
      </View>
      {/* Render child components */}
      <View style={{ flex: 1 }}>{children}</View>
    </View>
  );
}
```

{% endtab %}
{% endtabs %}

### Reference documents

* [Navigating screens](/documentation/api-and-sdk-en/react-native/screen-navigation/navigation.md)
* Using query parameters


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