iOS-常用的两个弹簧动画pop

POPSpringAnimation *popAna = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerPosition];
popAna.springBounciness = 10;
popAna.springSpeed = 10;
popAna.toValue = [NSValue valueWithCGPoint:CGPointMake(self.width/2, self.height/2 - 100)];

POPSpringAnimation *sprintAnimation = [POPSpringAnimation animationWithPropertyNamed:kPOPViewScaleXY];
sprintAnimation.toValue = [NSValue valueWithCGPoint:CGPointMake(1.0, 1.0)];
sprintAnimation.velocity = [NSValue valueWithCGPoint:CGPointMake(1.6, 1.6)];
sprintAnimation.springBounciness = 10.f;