Requests invocation of a block during rendering at specified time intervals.
- iOS 11.0+
- macOS 10.13+
- Mac Catalyst 13.0+
- tvOS 11.0+
- watchOS 6.0+
The specified time interval requesting block invocation during rendering.
The serial queue the block should be unqueued on. If you pass
NULL, the main queue is used. Passing a concurrent queue results in undefined behavior.
The block to be invoked periodically.
The block associated with this method is invoked at the specified time intervals, interpreted according to the timeline of the timebase. The block is also invoked whenever there is a time jump or rendering starts or stops.
If a very short time interval is used, the synchronizer may invoke the block less frequently than requested. However, the synchronizer will invoke the block often enough for the client to update indications of the current time appropriately in its end-user interface.
Always pair a call to this method with a call to
remove. Releasing the observer without calling
remove results in undefined behavior.