Retrieves the nominal refresh period of a display link.


func CVDisplayLinkGetNominalOutputVideoRefreshPeriod(_ displayLink: CVDisplayLink) -> CVTime



The display link whose refresh period you want to obtain.

Return Value

A CVTime structure that holds the nominal refresh period. This value is indefinite if an invalid display link was specified.


This call allows one to retrieve the device's ideal refresh period. For example, an NTSC output device might report 1001/60000 to represent the exact NTSC vertical refresh rate.

See Also

Inspecting Display Links

func CVDisplayLinkGetCurrentCGDisplay(CVDisplayLink) -> CGDirectDisplayID

Gets the current display associated with a display link.

func CVDisplayLinkGetCurrentTime(CVDisplayLink, UnsafeMutablePointer<CVTimeStamp>) -> CVReturn

Retrieves the current (“now”) time of a given display link.

func CVDisplayLinkTranslateTime(CVDisplayLink, UnsafePointer<CVTimeStamp>, UnsafeMutablePointer<CVTimeStamp>) -> CVReturn

Translates the time in the display link’s time base from one representation to another.

func CVDisplayLinkGetActualOutputVideoRefreshPeriod(CVDisplayLink) -> Double

Retrieves the actual output refresh period of a display as measured by the system time.

func CVDisplayLinkGetOutputVideoLatency(CVDisplayLink) -> CVTime

Retrieves the nominal latency of a display link.

func CVDisplayLinkIsRunning(CVDisplayLink) -> Bool

Indicates whether a given display link is running.

func CVDisplayLinkGetTypeID() -> CFTypeID

Obtains the Core Foundation ID for the display link data type.