Indicates the start point of the receiver as a fraction of the entire transition.
- iOS 2.0+
- macOS 10.5+
- Mac Catalyst 13.0+
- tvOS 9.0+
- Core Animation
Legal values are numbers between 0.0 and 1.0. For example, to start the transition half way through its progress set
start to 0.5. The default value is 0.