# CVDisplayLink A high-priority thread that notifies your app when a given display will need each frame. ## Overview A Core Video display link provides a separate high-priority thread to notify your application when a given display will need each frame. You can use a display link to easily synchronize with the refresh rate of a display. The display link API uses the Core Foundation class system internally to provide reference counting behavior and other useful properties. ## Topics ### Creating Display Links [`func CVDisplayLinkCreateWithCGDisplay(CGDirectDisplayID, UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkCreateWithCGDisplay(_:_:)) Creates a display link for a single display. [`func CVDisplayLinkCreateWithCGDisplays(UnsafeMutablePointer, CFIndex, UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkCreateWithCGDisplays(_:_:_:)) Creates a display link for an array of displays. [`func CVDisplayLinkCreateWithActiveCGDisplays(UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkCreateWithActiveCGDisplays(_:)) Creates a display link capable of being used with all active displays. [`func CVDisplayLinkCreateWithOpenGLDisplayMask(CGOpenGLDisplayMask, UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkCreateWithOpenGLDisplayMask(_:_:)) Creates a display link from an OpenGL display mask. ### Configuring Display Links [`func CVDisplayLinkSetCurrentCGDisplay(CVDisplayLink, CGDirectDisplayID) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkSetCurrentCGDisplay(_:_:)) Sets the current display of a display link. [`func CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(CVDisplayLink, CGLContextObj, CGLPixelFormatObj) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(_:_:_:)) Selects the display link most optimal for the current renderer of an OpenGL context. [`func CVDisplayLinkSetOutputCallback(CVDisplayLink, CVDisplayLinkOutputCallback?, UnsafeMutableRawPointer?) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkSetOutputCallback(_:_:_:)) Sets the renderer output callback function. [`func CVDisplayLinkSetOutputHandler(CVDisplayLink, CVDisplayLinkOutputHandler) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkSetOutputHandler(_:_:)) [`typealias CVDisplayLinkOutputHandler`](/documentation/CoreVideo/CVDisplayLinkOutputHandler) ### Inspecting Display Links [`func CVDisplayLinkGetCurrentCGDisplay(CVDisplayLink) -> CGDirectDisplayID`](/documentation/CoreVideo/CVDisplayLinkGetCurrentCGDisplay(_:)) Gets the current display associated with a display link. [`func CVDisplayLinkGetCurrentTime(CVDisplayLink, UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkGetCurrentTime(_:_:)) Retrieves the current (“now”) time of a given display link. [`func CVDisplayLinkTranslateTime(CVDisplayLink, UnsafePointer, UnsafeMutablePointer) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkTranslateTime(_:_:_:)) Translates the time in the display link’s time base from one representation to another. [`func CVDisplayLinkGetActualOutputVideoRefreshPeriod(CVDisplayLink) -> Double`](/documentation/CoreVideo/CVDisplayLinkGetActualOutputVideoRefreshPeriod(_:)) Retrieves the actual output refresh period of a display as measured by the system time. [`func CVDisplayLinkGetNominalOutputVideoRefreshPeriod(CVDisplayLink) -> CVTime`](/documentation/CoreVideo/CVDisplayLinkGetNominalOutputVideoRefreshPeriod(_:)) Retrieves the nominal refresh period of a display link. [`func CVDisplayLinkGetOutputVideoLatency(CVDisplayLink) -> CVTime`](/documentation/CoreVideo/CVDisplayLinkGetOutputVideoLatency(_:)) Retrieves the nominal latency of a display link. [`func CVDisplayLinkIsRunning(CVDisplayLink) -> Bool`](/documentation/CoreVideo/CVDisplayLinkIsRunning(_:)) Indicates whether a given display link is running. [`func CVDisplayLinkGetTypeID() -> CFTypeID`](/documentation/CoreVideo/CVDisplayLinkGetTypeID()) Obtains the Core Foundation ID for the display link data type. ### Retaining and Releasing Display Links [`extern void CVDisplayLinkRelease(CVDisplayLinkRef displayLink);`](/documentation/CoreVideo/CVDisplayLinkRelease) Releases a display link. [`extern CVDisplayLinkRefCVDisplayLinkRetain(CVDisplayLinkRef displayLink);`](/documentation/CoreVideo/CVDisplayLinkRetain) Retains a display link. ### Managing Display Links [`func CVDisplayLinkStart(CVDisplayLink) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkStart(_:)) Activates a display link. [`func CVDisplayLinkStop(CVDisplayLink) -> CVReturn`](/documentation/CoreVideo/CVDisplayLinkStop(_:)) Stops a display link. ### Data Types [`class CVDisplayLink`](/documentation/CoreVideo/CVDisplayLink) A reference to a display link object. [`typealias CVOptionFlags`](/documentation/CoreVideo/CVOptionFlags) The flags to be used for the display link output callback function. ### Callbacks [`typealias CVDisplayLinkOutputCallback`](/documentation/CoreVideo/CVDisplayLinkOutputCallback) A type for a display link callback function that the system invokes when it’s time for the app to output a video frame. [`typealias CVDisplayLinkOutputHandler`](/documentation/CoreVideo/CVDisplayLinkOutputHandler) --- 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)