---
title: AccessorySecuritySession.EventHandler
framework: accessorytransportextension
role: symbol
role_heading: Protocol
path: accessorytransportextension/accessorysecuritysession/eventhandler
---

# AccessorySecuritySession.EventHandler

A protocol that defines methods for handling security session events.

## Declaration

```swift
protocol EventHandler
```

## Mentioned in

Receiving iOS notifications on an accessory

## Overview

Overview Implement this protocol to respond to key exchange messages and session invalidation during the cryptographic key exchange process.

## Topics

### Handling security messages

- [messageReceived(_:completion:)](accessorytransportextension/accessorysecuritysession/eventhandler/messagereceived(_:completion:).md)

### Handling session life cycle

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

## See Also

### Handling session events

- [AccessorySecuritySession.Error](accessorytransportextension/accessorysecuritysession/error.md)