#import #import @interface UIView (AnimationUtils) + (double)animationDurationFactor; @end CABasicAnimation * _Nonnull makeSpringAnimation(NSString * _Nonnull keyPath); CABasicAnimation * _Nonnull makeSpringBounceAnimation(NSString * _Nonnull keyPath, CGFloat initialVelocity); CGFloat springAnimationValueAt(CABasicAnimation * _Nonnull animation, CGFloat t);