UIScrollView通过滚动方向和速度实现翻转

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{

    double curCallOffset = scrollView.contentOffset.x;

    double direction = curCallOffset - prevCallOffset;

    double curCallTime = CACurrentMediaTime();

    double timeDelta = curCallTime - prevCallTime;

    double offsetDelta = curCallOffset - prevCallOffset;

    double velocity = fabs(offsetDelta / timeDelta );

    

    if(velocity > 3000) velocity =3000;

    

    NSLog(@"%f",velocity);

    prevCallTime = curCallTime;

    prevCallOffset = curCallOffset;

    

        if (direction > 0) {

            CATransform3D rotationAndPerspectiveTransform =CATransform3DIdentity;

            rotationAndPerspectiveTransform.m34 =1.0 / -500;

            rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, (velocity/3000)*(-45.0f *M_PI) /180.0f, 0.0f, 1.0f,0.0f);

            layer.transform = rotationAndPerspectiveTransform;

            layer2.transform = rotationAndPerspectiveTransform;

            layer3.transform = rotationAndPerspectiveTransform;

            layer4.transform = rotationAndPerspectiveTransform;

            layer5.transform = rotationAndPerspectiveTransform;

            layer6.transform = rotationAndPerspectiveTransform;

            layer7.transform = rotationAndPerspectiveTransform;

        }

        else if (direction <0)

        {

            CATransform3D rotationAndPerspectiveTransform =CATransform3DIdentity;

            rotationAndPerspectiveTransform.m34 =1.0 / -500;

            rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, (velocity/3000)*(45.0f *M_PI) /180.0f, 0.0f, 1.0f,0.0f);

            layer.transform = rotationAndPerspectiveTransform;

            layer2.transform = rotationAndPerspectiveTransform;

            layer3.transform = rotationAndPerspectiveTransform;

            layer4.transform = rotationAndPerspectiveTransform;

            layer5.transform = rotationAndPerspectiveTransform;

            layer6.transform = rotationAndPerspectiveTransform;

            layer7.transform = rotationAndPerspectiveTransform;

        }

}

prevCallTime／prevCallOffset设置为全局变量，基于scrollViewDidScroll的实时动态行为，该变量并不用初始化。