---
title: FxPrincipalDelegate
framework: Professional Video Applications
role: symbol
role_heading: Protocol
platforms: [fxplug 4.1+]
path: professional_video_applications/fxprincipaldelegate
---

# FxPrincipalDelegate

A protocol that provides information about the host application that launched your XPC service.

## Declaration

```swift
protocol FxPrincipalDelegate
```

## Overview

Overview When the host application first launches your XPC Service, your XPC calls +startServicePrincipal(with:) to get communication with the host application started. Passing in a delegate allows you to know which host application and version launched your XPC service.

## Topics

### Instance Method

- [didEstablishConnection(withHost:version:)](professional_video_applications/fxprincipaldelegate/didestablishconnection(withhost:version:).md)

## See Also

### Services

- [FxPrincipal](professional_video_applications/fxprincipal.md)
- [FxPrincipalAPI](professional_video_applications/fxprincipalapi.md)