---
title: "setInterface(_:for:argumentIndex:ofReply:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/nsxpcinterface/setinterface(_:for:argumentindex:ofreply:)"
---

# setInterface(_:for:argumentIndex:ofReply:)

Configures a specific parameter of a method to be sent as a proxy object instead of copied.

## Declaration

```swift
func setInterface(_ ifc: NSXPCInterface, for sel: Selector, argumentIndex arg: Int, ofReply: Bool)
```

## Parameters

- `ifc`: The doc://com.apple.foundation/documentation/Foundation/NSXPCInterface object that describes the protocol for the proxy object. The interface is configured the same way as the interface for an exported object or remote object proxy.
- `sel`: Specifies which method in the protocol is being configured.
- `arg`: Specifies the position (starting at index 0) of the parameter for which you are configuring a proxy object. This may be either the position of a parameter in the method itself or the position in its reply block. This argument must be an object.
- `ofReply`: Pass doc://com.apple.documentation/documentation/Swift/true if arg is an index into the parameters of the reply block, or doc://com.apple.documentation/documentation/Swift/false if it is an index into the parameters of the method itself.

## Discussion

Discussion If an argument to a method in your protocol should be sent as a proxy object instead of by copy, then configure the interface for that protocol with a new interface for a specific argument. An example of an object that should be a proxy instead of being copied is a view object.