---
title: "CFNetServiceSetClient(_:_:_:)"
framework: cfnetwork
role: symbol
role_heading: Function
path: "cfnetwork/cfnetservicesetclient(_:_:_:)"
---

# CFNetServiceSetClient(_:_:_:)

Associates a callback function with a CFNetService or disassociates a callback function from a CFNetService.

## Declaration

```swift
func CFNetServiceSetClient(_ theService: CFNetService, _ clientCB: CFNetServiceClientCallBack?, _ clientContext: UnsafeMutablePointer<CFNetServiceClientContext>?) -> Bool
```

## Parameters

- `theService`: The CFNetService; cannot be NULL.
- `clientCB`: The callback function that is to be associated with this CFNetService. If you are shutting down the service, set clientCB to NULL to disassociate from this CFNetService the callback function that was previously associated.
- `clientContext`: Context information to be used when clientCB is called; cannot be NULL.

## Return Value

Return Value TRUE if the client was set; otherwise, FALSE.

## Discussion

Discussion The callback function specified by clientCB will be called to report IP addresses (in the case of CFNetServiceResolve) or to report registration errors (in the case of CFNetServiceRegister). Special Considerations This function is thread safe. For a CFNetService that will operate asynchronously, call this function and then call CFNetServiceScheduleWithRunLoop(_:_:_:) to schedule the service on a run loop. Then call CFNetServiceRegister or CFNetServiceResolve.

## See Also

### Network Services

- [CFNetService](cfnetwork/cfnetservice.md)
- [CFNetServiceBrowser](cfnetwork/cfnetservicebrowser.md)
- [CFNetServiceBrowserFlags](cfnetwork/cfnetservicebrowserflags.md)
- [CFNetServiceMonitor](cfnetwork/cfnetservicemonitor.md)
- [CFNetServiceMonitorType](cfnetwork/cfnetservicemonitortype.md)
- [CFNetServiceClientContext](cfnetwork/cfnetserviceclientcontext.md)
- [CFNetServiceRegisterFlags](cfnetwork/cfnetserviceregisterflags.md)
- [CFNetServicesError](cfnetwork/cfnetserviceserror.md)
- [CFNetServiceBrowserInvalidate(_:)](cfnetwork/cfnetservicebrowserinvalidate(_:).md)
- [CFNetServiceBrowserScheduleWithRunLoop(_:_:_:)](cfnetwork/cfnetservicebrowserschedulewithrunloop(_:_:_:).md)
- [CFNetServiceBrowserCreate(_:_:_:)](cfnetwork/cfnetservicebrowsercreate(_:_:_:).md)
- [CFNetServiceBrowserGetTypeID()](cfnetwork/cfnetservicebrowsergettypeid().md)
- [CFNetServiceBrowserSearchForDomains(_:_:_:)](cfnetwork/cfnetservicebrowsersearchfordomains(_:_:_:).md)
- [CFNetServiceBrowserSearchForServices(_:_:_:_:)](cfnetwork/cfnetservicebrowsersearchforservices(_:_:_:_:).md)
- [CFNetServiceBrowserStopSearch(_:_:)](cfnetwork/cfnetservicebrowserstopsearch(_:_:).md)