iOS实现卡片堆叠效果

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

 [self.viewArr enumerateObjectsUsingBlock:^(UIView * view, NSUInteger idx, BOOL *stop) {

 NSInteger value = self.distance;

 /*************设置位置***************/
 CGRect rect = view.frame;
 //view最底位置
 NSInteger min_y = self.top + value*idx;
 rect.origin.y = min_y - (scrollView.contentOffset.y);

 //view的最高位置
 if (scrollView.contentOffset.y >= value*idx-value*pow(2.0, idx)/pow(2.0, self.dataArr.count)){
  rect.origin.y = self.top+value*pow(2.0, idx)/pow(2.0, self.dataArr.count);
 }
 if (scrollView.contentOffset.y > scrollView.contentSize.height- SCREEN_HEIGTH) {
  rect.origin.y = rect.origin.y -(scrollView.contentOffset.y -(scrollView.contentSize.height-SCREEN_HEIGTH));
 }
 view.frame = rect;

 /*************设置大小***************/
 CGFloat scale = 0.60;
 scale = (rect.origin.y*0.75 +60)/1000+scale >=0.9?0.9:(rect.origin.y*0.75 +50)/1000+scale;
 view.layer.transform = CATransform3DMakeScale(scale, scale, 1);
 }];
}