Methods that model a hierarchical timing system, allowing objects to map time between their parent and local time.
- iOS 2.0+
- macOS 10.5+
- tvOS 9.0+
- Core Animation
Absolute time is defined as mach time converted to seconds. The
CACurrent function is provided as a convenience for getting the current absolute time.
The conversion from parent time to local time has two stages:
Conversion to “active local time.” This includes the point at which the object appears in the parent object's timeline and how fast it plays relative to the parent.
Conversion from “active local time” to “basic local time.” The timing model allows for objects to repeat their basic duration multiple times and, optionally, to play backwards before repeating.