A Boolean value indicating whether the animation is running in the reverse direction.
- iOS 10.0+
- tvOS 10.0+
When the value of this property is
true, animations run in the reverse direction—that is, view properties animate back to their original values. When the value is
false, view properties animate to their intended final values.
When implementing this property, changes should cause the animation to reverse direction. If you allow changes while the animation is running, it is best to pause the animation briefly and then start it again in the opposite direction. Once the animation transitions to the
UIView state, you can ignore changes to this property.