---
title: AccessoryWorker.FeatureSession.Handler
framework: Accessory Transport Extension
role: symbol
role_heading: Type Alias
platforms: [iOS 27.3+]
path: accessorytransportextension/accessoryworker/featuresession/handler
---

# AccessoryWorker.FeatureSession.Handler

A handler type for the session’s transport extension.

## Declaration

```swift
typealias Handler = AccessoryFeatureRuntimeSessionHandler<AccessoryWorker.FeatureSession>
```

## Mentioned in

Sending data to an accessory in the background

## Discussion

Discussion Create a handler type that conforms to this type alias to receive events from an AccessoryWorker.FeatureSession. Because each feature declares its own Handler type alias, your transport extension needs a distinct handler type for each feature it supports: the compiler rejects a handler written for AccessoryGPUWorker.FeatureSession if you pass it to this feature’s session, or any other feature’s session. Return an instance of your handler from the factory closure that you pass to makeFeatureSession(_:).