# CFNetServiceRegisterWithOptions(_:_:_:) Makes a CFNetService available on the network. ``` func CFNetServiceRegisterWithOptions(_ theService: CFNetService, _ options: CFOptionFlags, _ error: UnsafeMutablePointer?) -> Bool ``` ## Parameters `theService` Network service to register; cannot be `NULL`. The registration will fail if the service doesn’t have a domain, a type, a name, and an IP address. `options` Bit flags for specifying registration options. Currently, the only registration option is `kCFNetServiceFlagNoAutoRename`. For details, see `CFNetService Registration Options`. `error` Pointer to a structure that will be set to an error code and the error code’s domain if an error occurs; or `NULL` if you don’t want to receive the error code and its domain. ## Return Value `TRUE` if an asynchronous service registration was started; `FALSE` if an asynchronous or synchronous registration failed or if a synchronous registration was canceled. ## Discussion If the service is to run in asynchronous mode, you must call [`CFNetServiceSetClient(_:_:_:)`](/documentation/CFNetwork/CFNetServiceSetClient(_:_:_:)) to associate a callback function with this CFNetService before calling this function. When registering a service that runs in asynchronous mode, this function returns `TRUE` if the service contains all of the required attributes and the registration process can start. If the registration process completes successfully, the service is available on the network until you shut down the service by calling [`CFNetServiceUnscheduleFromRunLoop(_:_:_:)`](/documentation/CFNetwork/CFNetServiceUnscheduleFromRunLoop(_:_:_:)), [`CFNetServiceSetClient(_:_:_:)`](/documentation/CFNetwork/CFNetServiceSetClient(_:_:_:)), and [`CFNetServiceCancel(_:)`](/documentation/CFNetwork/CFNetServiceCancel(_:)). If the service does not contain all of the required attributes or if the registration process does not complete successfully, this function returns `FALSE`. When registering a service that runs in synchronous mode, this function blocks until an error occurs, in which case this function returns `FALSE`. Until this function returns `FALSE`, the service is available on the network. To force this function to return `FALSE`, thereby shutting down the service, call [`CFNetServiceCancel(_:)`](/documentation/CFNetwork/CFNetServiceCancel(_:)) from another thread. The `options` parameter is a bit flag for specifying service registration options. Currently, `kCFNetServiceFlagNoAutoRename` is the only supported registration option. If this bit is set and a service of the same name is running, the registration will fail. If this bit is not set and a service of the same name is running, the service that is being registered will be renamed automatically by appending `(`*n*`)` to the service name, where *n* is a number that is incremented until the service can be registered with a unique name. ### Special Considerations This function is thread safe. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)