---
title: AccessoryTransportSession.EventHandler
framework: accessorytransportextension
role: symbol
role_heading: Protocol
path: accessorytransportextension/accessorytransportsession/eventhandler
---

# AccessoryTransportSession.EventHandler

A protocol that defines methods for handling transport session events.

## Declaration

```swift
protocol EventHandler
```

## Overview

Overview Implement this protocol to respond to data events and session invalidation in your transport extension.

## Topics

### Handling data events

- [dataEventHandler(event:)](accessorytransportextension/accessorytransportsession/eventhandler/dataeventhandler(event:).md)
- [messageReceived(_:completion:)](accessorytransportextension/accessorytransportsession/eventhandler/messagereceived(_:completion:).md)

### Handling the session life cycle

- [invalidationHandler(error:)](accessorytransportextension/accessorytransportsession/eventhandler/invalidationhandler(error:).md)

### Instance Methods

- [sessionInvalidated(error:)](accessorytransportextension/accessorytransportsession/eventhandler/sessioninvalidated(error:).md)

## See Also

### Handling session events

- [AccessoryTransportSession.DataEvent](accessorytransportextension/accessorytransportsession/dataevent.md)