---
title: "Identity & Users"
description: "Identify customers, set properties, and reset identity on sign-out."
search:
  tags: ["sdk", "reference", "ios"]
  keywords: ["Swift", "StoreKit", "Xcode", "identify", "distinctId", "reset"]
---

The SDK starts with an anonymous identity, so your app can record activity before sign-in. Once a customer signs in, identify them with your application's account ID to bring their activity, purchases, and Feature access together across devices.

## Identifying a user

Call `identify()` after sign-in, or when your app restores a signed-in account:

```swift
// nuxie-doc-fragment: identify-user harness=sync-body
NuxieSDK.shared.identify(
    "user_12345",
    userProperties: [
        "plan": "premium",
        "signup_date": "2025-03-15"
    ],
    userPropertiesSetOnce: [
        "first_seen_platform": "ios"
    ]
)
```

Use the same stable account ID on every device and with a connected billing provider. Matching those identities lets Nuxie associate purchases and Feature access with the right customer. Your app handles sign-in; `identify()` associates Nuxie activity and access with that account.

### User properties

`userProperties` sets or overwrites values. `userPropertiesSetOnce` sets a value only when it is absent:

```swift
// nuxie-doc-fragment: update-user-properties harness=sync-body
NuxieSDK.shared.identify(
    "user_12345",
    userProperties: [
        "plan": "enterprise",       // Overwrites existing value
        "company": "Acme Inc"       // Sets new property
    ],
    userPropertiesSetOnce: [
        "first_login": "2025-01-01" // Only sets if not already present
    ]
)
```

Use these properties in [segments](/docs/guides/segments) and Experience personalization. Properties are delivered with the identity event and updated through profile synchronization.

## Reading the current identity

```swift
// nuxie-doc-fragment: inspect-user-identity harness=sync-body
// Get the effective distinct ID (identified ID if set, otherwise anonymous ID)
let distinctId = NuxieSDK.shared.getDistinctId()

// Get the anonymous ID (always available)
let anonId = NuxieSDK.shared.getAnonymousId()

// Check if the user is identified
let identified = NuxieSDK.shared.isIdentified
```

## Resetting identity (logout)

Call `reset()` when the customer signs out:

```swift
// nuxie-doc-fragment: reset-user harness=sync-body
NuxieSDK.shared.reset()
```

The SDK clears the identified customer and creates a new anonymous ID. Pass `keepAnonymousId: true` only when you want to preserve the existing anonymous ID:

```swift
// nuxie-doc-fragment: reset-user-preserving-anonymous-id harness=sync-body
NuxieSDK.shared.reset(keepAnonymousId: true)
```

### What happens during reset

The SDK clears the previous customer's active properties, feature access, and Experience state, then loads the new anonymous customer's profile. Subsequent events use the anonymous ID.

`reset()` changes Nuxie's identity on the device where you call it. Your app and authentication provider control sign-out and sessions on other devices. Call `reset()` on each device when its app session signs out.

## How identity works

On first launch, the SDK creates and stores an anonymous ID. It uses that ID until `identify()` selects a known customer.

### What happens during identify

When the ID changes, the SDK switches to that customer, restores their cached profile when available, and requests an updated profile. It sends `$identify` with the supplied properties. Calling `identify()` with the same ID and no properties makes no change and does not force a refresh.

## Anonymous-to-identified linking

On the first anonymous-to-identified transition, the SDK moves queued anonymous events to the identified customer. `$identify` includes the previous anonymous ID as `$anon_distinct_id`.

<span id="next-steps" />

See [Tracking events](/docs/ios-sdk/tracking-events) to record app activity and [Profile sync](/docs/ios-sdk/sessions-and-lifecycle) for update timing.