# Reset API in Mobile SDKs


This guide explains how to use the `reset` API in the RudderStack [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 `reset` API that lets you clear the persisted data, for example, user ID and traits.

The SDK also does the following once you call the `reset` API:

- Generates a new `anonymousId` (default behavior)
- If [session tracking]({{< ref "sources/event-streams/sdks/client-side-features/session-tracking.md" >}}) is enabled, clears the current `sessionId` and generates a new one.

{{< info >}}
If a mobile device mode integration plugin is present, then calling the `reset` API also triggers the integration's `reset` API — **provided it is supported**.
{{< /info >}}

The `reset` API supports the following invocations:

- [Default behavior](#default-behavior): Clears all persisted user data
- [Selective reset](#selective-reset): Choose specific data points to reset while preserving others

## Default behavior

By default, calling the `reset` API clears all persisted user data including user ID and traits, refreshes session information, and generates a new anonymous ID.

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
analytics.reset()
```

The corresponding Java snippet is shown below:

```java
analytics.reset();
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
analytics.reset()
```

The corresponding Objective-C snippet is shown below:

```objectivec
[analytics reset];
```
{{% /tab %}}
{{< /tabs >}}

## Selective reset

You can also use the `reset` API to choose which specific data components to reset while preserving others. This way, you have granular control over each component — you can regenerate the anonymous ID, clear the user ID, clear traits, or refresh session information, or preserve any of these values as per your requirement.

To perform a selective reset, the SDKs provide a `options` parameter that accepts a `ResetOptions` object with the following structure:

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
val options = ResetOptions(
  entries = ResetEntries(
    anonymousId = true,
    userId = true,
    traits = true,
    session = true
  )
)
analytics.reset(options)
```

The corresponding Java snippet is shown below:

```java
ResetEntriesBuilder entriesBuilder = new ResetEntriesBuilder()
  .setAnonymousId(true)
  .setUserId(true)
  .setTraits(true)
  .setSession(true);
ResetOptionsBuilder optionsBuilder = new ResetOptionsBuilder()
  .setEntries(entriesBuilder.build());
analytics.reset(optionsBuilder.build());
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
analytics.reset(options: ResetOptions(
  entries: ResetEntries(
    anonymousId: true,
    userId: true,
    traits: true,
    session: true
  )
))
```

The corresponding Objective-C snippet is shown below:

```objectivec
RSSResetEntriesBuilder *entriesBuilder = [RSSResetEntriesBuilder new];
[entriesBuilder setAnonymousIdResetEntry:YES];
[entriesBuilder setUserIdResetEntry:YES];
[entriesBuilder setTraitsResetEntry:YES];
[entriesBuilder setSessionResetEntry:YES];

RSSResetOptionsBuilder *optionsBuilder = [RSSResetOptionsBuilder new];
[optionsBuilder setEntries:[entriesBuilder build]];

[analytics resetWithOptions:[optionsBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}

### `entries` parameters

The following table describes the parameters accepted by the `entries` object of `ResetOptions`:

| Parameter | Description | Default value |
|-----------|-------------|---------------|
| `anonymousId` | Resets the anonymous user ID. | `true` |
| `userId` | Resets the persisted user ID. | `true` |
| `traits` | Resets the persisted user traits. | `true` |
| `session` | Resets the current session information. | `true` |

{{< info >}}
All entries in the `ResetOptions.entries` object are **optional**. If you do not specify any entry, the SDK sets its default value as described in the above table.
{{< /info >}}

### Examples

This section provides the following examples of performing a selective reset using the `reset` API:

- [Reset all data except session information](#reset-all-data-except-session-information)
- [Reset only session information](#reset-only-session-information)
- [Reset only user ID and traits](#reset-only-user-id-and-traits)

#### Reset all data except session information

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
analytics.reset(ResetOptions(
  entries = ResetEntries(
    anonymousId = true,
    userId = true,
    traits = true,
    session = false
  )
))
```

The corresponding Java snippet is shown below:

```java
ResetEntriesBuilder entriesBuilder = new ResetEntriesBuilder()
  .setAnonymousId(true)
  .setUserId(true)
  .setTraits(true)
  .setSession(false);
ResetOptionsBuilder optionsBuilder = new ResetOptionsBuilder()
  .setEntries(entriesBuilder.build());
analytics.reset(optionsBuilder.build());
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
analytics.reset(options: ResetOptions(
  entries: ResetEntries(
    anonymousId: true,
    userId: true,
    traits: true,
    session: false
  )
))
```

The corresponding Objective-C snippet is shown below:

```objectivec
RSSResetEntriesBuilder *entriesBuilder = [RSSResetEntriesBuilder new];
[entriesBuilder setAnonymousIdResetEntry:YES];
[entriesBuilder setUserIdResetEntry:YES];
[entriesBuilder setTraitsResetEntry:YES];
[entriesBuilder setSessionResetEntry:NO];

RSSResetOptionsBuilder *optionsBuilder = [RSSResetOptionsBuilder new];
[optionsBuilder setEntries:[entriesBuilder build]];

[analytics resetWithOptions:[optionsBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}

#### Reset only session information

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
analytics.reset(ResetOptions(
  entries = ResetEntries(
    anonymousId = false,
    userId = false,
    traits = false,
    session = true
  )
))
```

The corresponding Java snippet is shown below:

```java
ResetEntriesBuilder entriesBuilder = new ResetEntriesBuilder()
  .setAnonymousId(false)
  .setUserId(false)
  .setTraits(false)
  .setSession(true);
ResetOptionsBuilder optionsBuilder = new ResetOptionsBuilder()
  .setEntries(entriesBuilder.build());
analytics.reset(optionsBuilder.build());
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
analytics.reset(options: ResetOptions(
  entries: ResetEntries(
    anonymousId: false,
    userId: false,
    traits: false,
    session: true
  )
))
```

The corresponding Objective-C snippet is shown below:

```objectivec
RSSResetEntriesBuilder *entriesBuilder = [RSSResetEntriesBuilder new];
[entriesBuilder setAnonymousIdResetEntry:NO];
[entriesBuilder setUserIdResetEntry:NO];
[entriesBuilder setTraitsResetEntry:NO];
[entriesBuilder setSessionResetEntry:YES];

RSSResetOptionsBuilder *optionsBuilder = [RSSResetOptionsBuilder new];
[optionsBuilder setEntries:[entriesBuilder build]];

[analytics resetWithOptions:[optionsBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}

#### Reset only user ID and traits

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
analytics.reset(ResetOptions(
  entries = ResetEntries(
    anonymousId = false,
    userId = true,
    traits = true,
    session = false
  )
))
```

The corresponding Java snippet is shown below:

```java
ResetEntriesBuilder entriesBuilder = new ResetEntriesBuilder()
  .setAnonymousId(false)
  .setUserId(true)
  .setTraits(true)
  .setSession(false);
ResetOptionsBuilder optionsBuilder = new ResetOptionsBuilder()
  .setEntries(entriesBuilder.build());
analytics.reset(optionsBuilder.build());
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
analytics.reset(options: ResetOptions(
  entries: ResetEntries(
    anonymousId: false,
    userId: true,
    traits: true,
    session: false
  )
))
```

The corresponding Objective-C snippet is shown below:

```objectivec
RSSResetEntriesBuilder *entriesBuilder = [RSSResetEntriesBuilder new];
[entriesBuilder setAnonymousIdResetEntry:NO];
[entriesBuilder setUserIdResetEntry:YES];
[entriesBuilder setTraitsResetEntry:YES];
[entriesBuilder setSessionResetEntry:NO];

RSSResetOptionsBuilder *optionsBuilder = [RSSResetOptionsBuilder new];
[optionsBuilder setEntries:[entriesBuilder build]];

[analytics resetWithOptions:[optionsBuilder build]];
```
{{% /tab %}}
{{< /tabs >}}

## Implicit reset via `identify`

The [`identify`]({{< ref "sources/event-streams/sdks/mobile-sdk-apis/identify.md" >}}) API internally calls `reset()` when the `userId` changes. This is an implicit reset — it uses default `ResetOptions` (all entries reset to `true`). See the following scenarios for more information:

| <div style="width:350px">Scenario</div> | Reset triggered?  | What is reset |
| :----| :-----| :-----|
| `identify` on anonymous user (no prior `userId`) | No | Nothing |
| `identify` with the same `userId` | No | Nothing  |
| `identify` with a different `userId` (User A > User B) | Yes | <ul><li>`anonymousId` regenerated</li><li>`userId` cleared</li><li>`traits` cleared</li><li>`sessionId` refreshed</li></ul> |

You cannot pass custom `ResetOptions` to the implicit reset. To preserve specific entries (for example, to keep the session intact during a user switch), call `reset` explicitly with your desired options before calling `identify`.

**Why this works**: The explicit `reset` call clears the userId (since `userId = true`). When you call `identify` subsequently, the SDK sees that no previous `userId` is set - so it treats this as an anonymous-to-identified transition and skips the implicit reset entirely. This way, any entries you chose to preserve in the explicit reset (for example, `session = false`) remain untouched.

{{< tabs tabTotal="2" >}}
{{% tab tabName="Android (Kotlin)" %}}
```kotlin
// Preserve session while switching users

analytics.reset(ResetOptions(
    entries = ResetEntries(
        anonymousId = true,
        userId = true, // Should be set to `true` — otherwise the approach will not work.
        traits = true,
        session = false  // Preserve session
    )
))
analytics.identify(userId = "new-user-id")
```

The corresponding Java snippet is shown below:

```java
// Preserve session while switching users

ResetEntriesBuilder entriesBuilder = new ResetEntriesBuilder()
  .setAnonymousId(true)
  .setUserId(true) // Should be set to true — otherwise this approach won't work.
  .setTraits(true)
  .setSession(false);  // Preserve session
ResetOptionsBuilder optionsBuilder = new ResetOptionsBuilder()
  .setEntries(entriesBuilder.build());
analytics.reset(optionsBuilder.build());
analytics.identify("new-user-id");
```
{{% /tab %}}
{{% tab tabName="iOS (Swift)" %}}
```swift
// Preserve session while switching users

analytics.reset(options: ResetOptions(
    entries: ResetEntries(
        anonymousId: true,
        userId: true, // Should be set to `true` — otherwise the approach will not work.
        traits: true,
        session: false  // Preserve session
    )
))
analytics.identify(userId: "new-user-id")
```

The corresponding Objective-C snippet is shown below:

```objectivec
// Preserve session while switching users

RSSResetEntriesBuilder *entriesBuilder = [RSSResetEntriesBuilder new];
[entriesBuilder setAnonymousIdResetEntry:YES];
[entriesBuilder setUserIdResetEntry:YES]; // Should set to YES — otherwise this approach won't work.
[entriesBuilder setTraitsResetEntry:YES];
[entriesBuilder setSessionResetEntry:NO];  // Preserve session

RSSResetOptionsBuilder *optionsBuilder = [RSSResetOptionsBuilder new];
[optionsBuilder setEntries:[entriesBuilder build]];

[analytics resetWithOptions:[optionsBuilder build]];
[analytics identify:@"new-user-id"];
```
{{% /tab %}}
{{< /tabs >}}