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# CFNetServiceResolve

This function updates the specified CFNetService with the IP address or addresses associated with the service. Call [`CFNetServiceGetAddressing(_:)`](/documentation/CFNetwork/CFNetServiceGetAddressing(_:)) to get the addresses.

```
extern Boolean CFNetServiceResolve(CFNetServiceRef theService, CFStreamError *error);
```

## Parameters

`theService`

The CFNetService to resolve; cannot be `NULL`. The resolution will fail if the service doesn’t have a domain, a type, and a name.

`error`

A pointer to a <doc://com.apple.documentation/documentation/CoreFoundation/CFStreamError> 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 resolution was started or if a synchronous service resolution updated the CFNetService; `FALSE` if an asynchronous or synchronous resolution failed or if a synchronous resolution was canceled.

## Discussion

When resolving a service that runs in asynchronous mode, this function returns `TRUE` if the CFNetService has a domain, type, and name, and the underlying resolution process was started. Otherwise, this function returns `FALSE`. Once started, the resolution continues until it is canceled by calling [`CFNetServiceCancel(_:)`](/documentation/CFNetwork/CFNetServiceCancel(_:)).

When resolving a service that runs in synchronous mode, this function blocks until the CFNetService is updated with at least one IP address, until an error occurs, or until [`CFNetServiceCancel(_:)`](/documentation/CFNetwork/CFNetServiceCancel(_:)) is called.

### Special Considerations

This function is thread safe.

If the service will be used in asynchronous mode, you must call [`CFNetServiceSetClient(_:_:_:)`](/documentation/CFNetwork/CFNetServiceSetClient(_:_:_:)) before calling this function.

---

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