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# AVExternalSyncDevice.DiscoverySession

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

```
class DiscoverySession
```

## Overview

[`AVExternalSyncDevice.DiscoverySession`](/documentation/AVFoundation/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`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession/devices) property for changes to the external sync devices list.

## Topics

### Accessing the shared instance

[`shared`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession/shared)

The singleton instance of the external sync source device discovery session.

[`isSupported`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession/isSupported)

Whether external sync devices are supported by this device.

### Finding devices

[`devices`](/documentation/AVFoundation/AVExternalSyncDevice/DiscoverySession/devices)

An array of external sync devices connected to this host.


---

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