identify()

The identify() method links an anonymous app user to a known identity. Call it when the user logs in, registers, or updates their profile.

Syntax

iOS (Swift)

Datafly.shared.identify(userId: String, traits: [String: Any]? = nil)

Android (Kotlin)

Datafly.identify(userId: String, traits: Map<String, Any>? = null)

React Native / Cordova

Datafly.identify(userId, traits?)

Flutter

await Datafly.identify(userId, traits: {...})

Parameters

Basic usage

// iOS -- after login
Datafly.shared.identify(userId: "user-123", traits: [
    "email": "jane@example.com",
    "name": "Jane Doe",
    "plan": "professional",
])

// Android -- after login
Datafly.identify("user-123", mapOf(
    "email" to "jane@example.com",
    "name" to "Jane Doe",
    "plan" to "professional"
))

How identity works on mobile

When identify() is called:

1. The userId is stored in memory and included in all subsequent events
2. Traits are merged with previously set traits (new values overwrite existing keys)
3. An identify event is sent to your Signal endpoint
4. The server links userId to the anonymousId, creating a unified profile

Before identify():
  anonymousId: "a1b2c3d4-..."  (unknown user)

After identify("user-123"):
  anonymousId: "a1b2c3d4-..."  (linked)
  userId: "user-123"            (known user)

All subsequent track() and screen() calls include both anonymousId and userId.

PII handling

Trait merging

Traits merge across multiple identify() calls:

// First call
Datafly.shared.identify(userId: "user-123", traits: ["email": "jane@example.com", "plan": "starter"])
 
// Later call -- plan updated, email preserved
Datafly.shared.identify(userId: "user-123", traits: ["plan": "professional"])
 
// Internal state: { email: "jane@example.com", plan: "professional" }

Common traits

Trait names are snake_case, the names every integration blueprint reads (first_name, last_name, address.postal_code). Earlier versions of this page showed camelCase names; Signal still accepts firstName, lastName, createdAt, dateOfBirth, jobTitle and address.postalCode and renames them to their snake_case form when the event arrives, so existing sites keep working. If you send both spellings of one trait, the snake_case value is used. Your own trait names are never renamed.