Gets the IP address or addresses for a CFNetService.


func CFNetServiceResolveWithTimeout(_ theService: CFNetService, _ timeout: CFTimeInterval, _ error: UnsafeMutablePointer<CFStreamError>?) -> Bool



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


Value of type CFTimeInterval specifying the maximum amount of time allowed to perform the resolution. If the resolution is not performed within the specified amount of time, a timeout error will be returned. If timeout is less than or equal to zero, an infinite amount of time is allowed.


Pointer to a 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 timed out, or if a synchronous resolution was canceled.


This function updates the specified CFNetService with the IP address or addresses associated with the service. Call CFNetServiceGetAddressing(_:) to get the addresses.

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(_:).

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(_:) is called.

Special Considerations

This function is thread safe.

If the service will be used in asynchronous mode, you must call CFNetServiceSetClient(_:_:_:) before calling this function.

See Also

Network Services

class CFNetService

An opaque reference representing a CFNetService.

class CFNetServiceBrowser

An opaque reference representing a CFNetServiceBrowser.

class CFNetServiceMonitor

An opaque reference for a service monitor.

enum CFNetServiceMonitorType

Record type specifier used to tell a service monitor the type of record changes to watch for.

struct CFNetServiceClientContext

A structure provided when a CFNetService is associated with a callback function or when a CFNetServiceBrowser is created.

enum CFNetServicesError

Error codes that may be returned by CFNetServices functions or passed to CFNetServices callback functions.

func CFNetServiceBrowserInvalidate(CFNetServiceBrowser)

Invalidates an instance of a Network Service browser object.

func CFNetServiceBrowserGetTypeID() -> CFTypeID

Gets the Core Foundation type identifier for the Network Service browser object.

func CFNetServiceBrowserUnscheduleFromRunLoop(CFNetServiceBrowser, CFRunLoop, CFString)

Unschedules a CFNetServiceBrowser from a run loop and mode.

func CFNetServiceCancel(CFNetService)

Cancels a service registration or a service resolution.

func CFNetServiceGetPortNumber(CFNetService) -> Int32

This function gets the port number from a CFNetService.

func CFNetServiceGetTXTData(CFNetService) -> Unmanaged<CFData>?

Queries a network service for the contents of its TXT records.

func CFNetServiceGetTypeID() -> CFTypeID

Gets the Core Foundation type identifier for the Network Service object.

func CFNetServiceMonitorGetTypeID() -> CFTypeID

Gets the Core Foundation type identifier for all CFNetServiceMonitor instances.

func CFNetServiceMonitorInvalidate(CFNetServiceMonitor)

Invalidates an instance of a Network Service monitor object.

func CFNetServiceSetClient(CFNetService, CFNetServiceClientCallBack?, UnsafeMutablePointer<CFNetServiceClientContext>?) -> Bool

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

func CFNetServiceSetTXTData(CFNetService, CFData) -> Bool

Sets the TXT record for a CFNetService.