需求：拖动ScrollView 旋转另一个View。
设置锚点 '_imgView.layer.anchorPoint' 告诉从哪里旋转 设置初始状态_imgView.layer.transform = CATransform3DMakeRotation(-M_PI_2, 1, 0, 0); 设置scrollview代理 根据拖动的contentOffset 设置旋转的大小进度！
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 20, self.view.frame.size.width, self.view.frame.size.height-20)]; scrollView.delegate = self; scrollView.backgroundColor = [UIColor clearColor]; [self.view addSubview:scrollView]; scrollView.contentSize =CGSizeMake(self.view.frame.size.width, 1000);
_imgView = [[UIImageView alloc] initWithFrame:CGRectMake(self.view.frame.size.width / 2 - headHeight / 2, 0, headHeight,headHeight)];
_imgView.image = [UIImage imageNamed:@"1"];
[self.view addSubview:self.imgView];
_imgView.layer.anchorPoint = CGPointMake(0.5, 0);
here_imgView.layer.transform = CATransform3DMakeRotation(-M_PI_2, 1, 0, 0);
-(void)scrollViewDidScroll:(UIScrollView )scrollView{
NSLog(@"scrollview offset;%f",scrollView.contentOffset.y);
CGFloat offsetX = scrollView.contentOffset.y;
if (offsetX > -headHeight && offsetX < 0) { CGFloat angle = -M_PI_2 offsetX / headHeight;
_imgView.layer.transform = CATransform3DRotate(CATransform3DMakeRotation(-M_PI_2, 1, 0, 0), angle, 1, 0, 0); }
}
