# Group API in Mobile SDKs


This guide explains how to use the `group` API in the [Android (Kotlin)]({{< ref "sources/event-streams/sdks/kotlin-sdk/" >}}) and [iOS (Swift)]({{< ref "sources/event-streams/sdks/swift-sdk/" >}}) SDKs.

## Overview

The RudderStack Android (Kotlin) and iOS (Swift) SDKs provide a [`group`]({{< ref "event-spec/standard-events/group.md" >}}) API that lets you link an identified user with a group like a company, organization, or an account. You can also record any custom traits associated with that group like the company name, number of employees, etc.

{{< info >}}
You can link an identified user to multiple groups.
{{< /info >}}

## Android (Kotlin)

The `group` method definition in the Android (Kotlin) SDK is as follows:

{{< tabs tabTotal="2" >}}
{{% tab tabName="Default invocation" %}}
```kotlin
analytics.group(
    groupId = "<groupId>",
    traits = buildJsonObject {
        put("key", "value")
    },
    options = RudderOption(),
)
```

The corresponding Java snippet is shown below:

```java
HashMap<String, Object> traits = new HashMap<>();
traits.put("key", "value");

analytics.group("<groupId>", traits, new RudderOption());
```
{{% /tab %}}
{{% tab tabName="Alternate invocations" %}}
```kotlin
// Group event with groupId
analytics.group(
    groupId = "<groupId>"
)

// Group event with groupId and traits
analytics.group(
    groupId = "<groupId>",
    traits = buildJsonObject {
        put("key", "value")
    }
)

// Group event with groupId, traits and options
analytics.group(
    groupId = "<groupId>",
    traits = buildJsonObject {
        put("key", "value")
    },
    options = RudderOption(
        customContext = buildJsonObject {
            put("key", "value")
        },
        integrations = buildJsonObject {
            put("Amplitude", true)
            put("INTERCOM", buildJsonObject {
                put("field", "value")
            })
        },
        externalIds = listOf(
            ExternalId(type = "<id_type>", id = "<value>")
        )
    )
)
```
{{% /tab %}}
{{< /tabs >}}

### Method signature {#method-signature-kotlin}

The below table describes the `group` method signature in detail:

| Field | Data type | Description |
| :----| :------| :-----|
| `groupId` | String | The group's unique identifier in your database. |
| `traits` | Traits | Contains traits associated with the group. They are added in the root level of the event.<br /><br />Note that:<br /><br /><ul><li>RudderStack does not store any group traits.</li><li>The `traits` type in Java is `Map<String, Object>`.</li></ul> |
| `options` | RudderOption | Additional event options. |

### Example {#example-kotlin}

A sample `group` event sent from the Android (Kotlin) SDK is shown below:

{{< tabs tabTotal="2" >}}
{{% tab tabName="Kotlin" %}}
```kotlin
analytics.group(
    groupId = "5e8a78ba9d32d3b1898a6247",
    traits = buildJsonObject {
        put("name", "RudderStack")
    },
    options = RudderOption(
        customContext = buildJsonObject {
            put("plan", "Basic")
        },
        integrations = buildJsonObject {
            put("Amplitude", true)
            put("INTERCOM", buildJsonObject {
                put("lookup", "phone")
            })
        },
        externalIds = listOf(
            ExternalId(type = "brazeExternalId", id = "value1234")
        )
    )
)
```
{{% /tab %}}
{{% tab tabName="Java" %}}
```java
HashMap<String, Object> traits = new HashMap<>();
traits.put("name", "RudderStack");

Map<String, Object> customContext = new HashMap<>();
customContext.put("plan", "Basic");

Map<String, Object> nestedIntegrations = new HashMap<>();
nestedIntegrations.put("lookup", "phone");
Map<String, Object> integrations = new HashMap<>();
integrations.put("Amplitude", true);
integrations.put("INTERCOM", nestedIntegrations);

List<ExternalId> externalIds = new ArrayList<>();
externalIds.add(new ExternalId("brazeExternalId", "value1234"));

RudderOption option = new RudderOptionBuilder()
    .setIntegrations(integrations)
    .setExternalId(externalIds)
    .setCustomContext(customContext)
    .build();

analytics.group("5e8a78ba9d32d3b1898a6247", traits, option);
```
{{% /tab %}}
{{< /tabs >}}

## iOS (Swift)

The `group` method definition in the iOS (Swift) SDK is as follows:

{{< tabs tabTotal="2" >}}
{{% tab tabName="Default invocation" %}}
```swift
analytics.group(
    groupId: "<groupId>",
    traits: [
        "key": "value"
    ],
    options: RudderOption()
)
```

{{< warning >}}
Make sure to include the `import RudderStackAnalytics` statement before making the call.
{{< /warning >}}

The corresponding Objective-C snippet is shown below:

```objectivec
[analytics group:@"<groupId>" traits:@{@"key": @"value"} options:[[RSSOptionBuilder new] build]];
```

{{< info >}}
`RSSOptionBuilder` is an Objective-C–only helper class. It uses the builder pattern to create an `RSSOption` instance and lets you set custom context, configure integrations, and attach external IDs in a structured way.
{{< /info >}}

{{% /tab %}}
{{% tab tabName="Alternate invocations" %}}
```swift
// Group event with groupId
analytics.group(groupId: "some_group_id")

// Group event with groupId and traits
analytics.group(
    groupId: "group_id",
    traits: [
        "key-1": "value-1"
    ]
)

// Group event with groupId, traits and options
analytics.group(
    groupId: "some_group_id",
    traits: [
        "key-1": "value-1"
    ],
    options: RudderOption(
        integrations: [
            "Amplitude": true,
            "INTERCOM": [
                "lookup": "phone"
            ]
        ],
        customContext: [
            "key-1": "value-1"
        ],
        externalIds: [
            ExternalId(type: "brazeExternalId", id: "value1234")
        ]
    )
)
```

The corresponding Objective-C snippet is shown below:

```objectivec
// Group event with groupId
[analytics group:@"some_group_id"];

// Group event with groupId and traits
[analytics group:@"some_group_id"
         traits:@{
             @"key-1": @"value-1"
         }];

// Group event with groupId, traits and options
RSSOptionBuilder *optionBuilder = [[RSSOptionBuilder alloc] init];

[optionBuilder setCustomContext:@{
    @"key-1": @"value-1"
}];

[optionBuilder setIntegrations:@{
    @"Amplitude": @YES,
    @"INTERCOM": @{
        @"lookup": @"phone"
    }
}];

[optionBuilder setExternalIds:@[
    [[RSSExternalId alloc] initWithType:@"brazeExternalId" id:@"value1234"]
]];

[analytics group:@"some_group_id"
         traits:@{
             @"key-1": @"value-1"
         }
        options:[optionBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}

### Method signature {#method-signature-swift}

The below table describes the `group` method signature in detail:

| Field | Data type | Description |
| :----| :------| :-----|
| `groupId` | String | The group's unique identifier in your database. |
| `traits` | Traits | Contains traits associated with the group. They are added in the root level of the event. |
| `options` | RudderOption | Additional event options. |

### Example {#example-swift}

A sample `group` event sent from the iOS (Swift) SDK is shown below:

{{< tabs tabTotal="2" >}}
{{% tab tabName="Swift" %}}
```swift
analytics.group(
    groupId: "some_group_id",
    traits: [
        "key-1": "value-1"
    ],
    options: RudderOption(
        integrations: [
            "Amplitude": true,
            "INTERCOM": [
                "lookup": "phone"
            ]
        ],
        customContext: [
            "key-1": "value-1"
        ],
        externalIds: [
            ExternalId(type: "brazeExternalId", id: "value1234")
        ]
    )
)
```
{{% /tab %}}
{{% tab tabName="Objective-C" %}}
```objectivec
RSSOptionBuilder *optionBuilder = [[RSSOptionBuilder alloc] init];

[optionBuilder setCustomContext:@{
    @"key-1": @"value-1"
}];

[optionBuilder setIntegrations:@{
    @"Amplitude": @YES,
    @"INTERCOM": @{
        @"lookup": @"phone"
    }
}];

[optionBuilder setExternalIds:@[
    [[RSSExternalId alloc] initWithType:@"brazeExternalId" id:@"value1234"]
]];

[analytics group:@"some_group_id"
         traits:@{
             @"key-1": @"value-1"
         }
        options:[optionBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}