currentValue
The current value of the animation effect, based on the current progress
Declaration
var currentValue: Float { get }Discussion
An NSAnimation object gets the current value from delegate’s animation(_:valueForProgress:) method. If that method is not implemented, the animation computes the current value from the current progress by factoring in the animation curve. An animation object does not access this property directly. Instances of NSAnimation subclasses or other objects can invoke this method on a periodic basis to get the current value.
Subclasses may override this property and return a custom curve value instead of implementing animation(_:valueForProgress:), thereby saving on the overhead of using a delegate. The current value can be less than 0.0 or greater than 1.0. For example, if you make the value greater than 1.0 you can achieve a “rubber effect” where the size of a view is temporarily larger before its final size.