---
title: AVExternalSyncDevice.DiscoverySession
framework: avfoundation
role: symbol
role_heading: Class
path: avfoundation/avexternalsyncdevice/discoverysession
---

# AVExternalSyncDevice.DiscoverySession

A means of discovering and monitoring connection / disconnection of external sync devices to the host.

## Declaration

```swift
class DiscoverySession
```

## Overview

Overview AVExternalSyncDevice.DiscoverySession is a singleton that lists the external sync devices connected to the host. The client is expected to key-value observe the devices property for changes to the external sync devices list.

## Topics

### Accessing the shared instance

- [shared](avfoundation/avexternalsyncdevice/discoverysession/shared.md)
- [isSupported](avfoundation/avexternalsyncdevice/discoverysession/issupported.md)

### Finding devices

- [devices](avfoundation/avexternalsyncdevice/discoverysession/devices.md)

## Relationships

### Inherits From

- [NSObject](objectivec/nsobject-swift.class.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### External synchronization

- [AVExternalSyncDevice](avfoundation/avexternalsyncdevice.md)
- [AVExternalSyncDeviceDelegate](avfoundation/avexternalsyncdevicedelegate.md)
- [AVExternalSyncDeviceStatus](avfoundation/avexternalsyncdevicestatus.md)