# Custom Plugin Use Cases in Mobile SDKs


This guide covers the different use cases for [custom plugins]({{< ref "sources/event-streams/sdks/client-side-features/plugin-architecture/_index.md#custom-plugins" >}}) in the RudderStack [Android (Kotlin)]({{< ref "sources/event-streams/sdks/kotlin-sdk/" >}}) and [iOS (Swift)]({{< ref "sources/event-streams/sdks/swift-sdk/" >}}) SDKs, along with the expected event payload and links to the source code.

## Overview

RudderStack maintains sample custom plugins in the [Android (Kotlin)](https://github.com/rudderlabs/rudder-sdk-kotlin/tree/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins) and [iOS (Swift)](https://github.com/rudderlabs/rudder-sdk-swift/tree/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins) SDK sample applications. You can use these plugins as reference implementations to build your own custom plugins.

## User agent collection

These plugins add user agent information to the event context for better device identification. They populate the `context.userAgent` field.

### Android (Kotlin)

Use `UserAgentPlugin` to add user agent information to events.

Find the source code for this plugin [here](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/UserAgentPlugin.kt).

### iOS (Swift)

Two plugins are available for user agent collection:

| Name | Description | Source code |
| :----| :----| :----|
| `DynamicUserAgentPlugin` | Fetches user agent information dynamically using WebKit. | [Here](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/DynamicUserAgentPlugin.swift) |
| `StaticUserAgentPlugin` | Adds platform-specific static user agent information to events. | [Here](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/StaticUserAgentPlugin.swift) |

#### Sample payload

```json
{
	// ....
  "context": {
	   // ....
    "userAgent": "Dalvik/2.1.0 (Linux; U; Android 16; sdk_gphone64_arm64 Build/BE2A.250530.026.D1)"
  },
  // ....
}
```

## Push notification token

Use `SetPushTokenPlugin` to add push notification tokens to the event's device context for targeted messaging. It populates the `context.device.token` field.

Find the source code for this plugin in the following locations:

- [Android (Kotlin)](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/SetPushTokenPlugin.kt)
- [iOS (Swift)](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/SetPushTokenPlugin.swift)

#### Sample payload

```json
{
  // ....
  "context": {
    // ....
    "device": {
      // ...
      "token": "<TOKEN_VALUE>",
      // ...
    },
    // ....
  },
  // ....
}
```

## Override anonymous ID

Use `SetAnonymousIdPlugin` to replace the default SDK-generated anonymous ID with a custom value in the event payload. It populates the `anonymousId` field.

Find the source code for this plugin in the following locations:

- [Android (Kotlin)](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/SetAnonymousIdPlugin.kt)
- [iOS (Swift)](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/SetAnonymousIdPlugin.swift)

## Global event options

The `OptionPlugin` adds global custom context, integrations, and external IDs to all events. It populates the following fields:

- `context.externalId`
- Custom context in `context`
- `integrations`

Find the source code for this plugin in the following locations:

- [Android (Kotlin)](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/OptionPlugin.kt)
- [iOS (Swift)](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/OptionPlugin.swift)

#### Sample payload

```json
{
  // ....
  "context": {
    // ....
    "externalId": [
      {
        "id": "someValue",
        "type": "globalExternalId"
      }
    ],
    "sampleKey": "sampleValue", // Custom context
    // ....
  },
  "integrations": {
    "All": true,
    "CleverTap": true
  },
  // ....
}
```

## Collect advertising ID

Use the plugins in this section to collect and add the advertising ID and ad tracking status to events. They populate the following fields:

- `context.device.advertisingId`
- `context.device.adTrackingEnabled`

### Android (Kotlin)

Use `AndroidAdvertisingIdPlugin` to collect and add the Google Advertising ID (GAID) or Amazon Fire Advertising ID and ad tracking status.

Find the source code for this plugin [here](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/AndroidAdvertisingIdPlugin.kt).

### iOS (Swift)

Use `AdvertisingIdPlugin` to collect and add the iOS Advertising Identifier (IDFA) with ATT compliance.

Find the source code for this plugin [here](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/AdvertisingIdPlugin.swift).

#### Sample payload

```json
{
  // ....
  "context": {
    // ....
    "device": {
      "adTrackingEnabled": true,
      "advertisingId": "6934136c-002f-4b4d-8088-90cd71497a3a",
    },
    // ....
  },
  // ....
}
```

## Event filtering

Use `EventFilteringPlugin` to filter out specific analytics events from being processed by the SDK.

Find the source code for this plugin in the following locations:

- [Android (Kotlin)](https://github.com/rudderlabs/rudder-sdk-kotlin/blob/main/app/src/main/java/com/rudderstack/sampleapp/analytics/customplugins/EventFilteringPlugin.kt)
- [iOS (Swift)](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/EventFilteringPlugin.swift)

## Add Bluetooth information (iOS)

{{< warning >}}
This plugin is available only for the iOS (Swift) SDK.
{{< /warning >}}

Use `BluetoothInfoPlugin` to add Bluetooth availability information to the network context. It populates the `context.network.bluetooth` field.

Find the source code for this plugin [here](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/BluetoothInfoPlugin.swift).

#### Sample payload

```json
{
    // ....
    "context": {
        // ....
        "network": {
            "bluetooth": true,
        },
        // ....
    },
    // ....
}
```

## Get ATT tracking status (iOS)

{{< warning >}}
This plugin is available only for the iOS (Swift) SDK.
{{< /warning >}}

Use `SetATTTrackingStatusPlugin` to set a custom App Tracking Transparency (ATT) status in the device context. It populates the `context.device.attTrackingStatus` field.

Find the source code for this plugin [here](https://github.com/rudderlabs/rudder-sdk-swift/blob/main/Examples/SwiftUIExample/SwiftUIExample/CustomPlugins/SetATTTrackingStatusPlugin.swift).

#### Sample payload

```json
{
    // ....
    "context": {
        // ....
        "device": {
            "attTrackingStatus": 0,
        },
    },
    // ....
}
```

## See more

- [Plugin Architecture in Mobile SDKs]({{< ref "sources/event-streams/sdks/client-side-features/plugin-architecture/" >}}): Understand the plugin system and how to create custom plugins
- [Create Custom Plugin]({{< ref "sources/event-streams/sdks/client-side-features/plugin-architecture/create-custom-plugin.md" >}}): Steps to create a custom plugin
- [How to Use Device Mode Integrations]({{< ref "sources/event-streams/sdks/device-mode-integrations/usage.md#add-custom-plugins-to-integrations" >}}): Add custom plugins to device mode integrations