Directs a custom video compositor object to create a new pixel buffer composed asynchronously from a collection of sources.
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
An instance of
AVAsynchronousthat provides context for the requested composition.
Video Composition Request
If you intend to finish rendering the frame after handling of this message returns, you must retain
async until after composition is finished.
Note that if the custom compositor's implementation of this method returns without finishing the composition immediately, it may be invoked again with another composition request before the prior request is finished; in such cases the custom compositor should be prepared to manage multiple composition requests.
If the rendered frame is exactly the same as one of the source frames, with no letterboxing, pillboxing or cropping needed, then the appropriate source pixel buffer may be returned, after
CFRetain has been called on it).