Ios 实现 滑动cell 伸缩的核心代码

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat viewHeight = scrollView.height + scrollView.contentInset.top;
    NSArray *cells = self.tableView.visibleCells;
    for (int i = 0; i < cells.count; i++) {
        
        UITableViewCell *cell = cells[i];
        
        CGFloat y = cell.centerY - scrollView.contentOffset.y;
        CGFloat p = y - viewHeight / 2;
        
        CGFloat scale = cos(p / viewHeight * 0.8) * 0.85;
        
        [UIView animateWithDuration:0.15 delay:0 options:UIViewAnimationOptionCurveEaseInOut|UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionBeginFromCurrentState animations:^{
            
            cell.transform = CGAffineTransformMakeScale(scale, scale);
            
        } completion:^(BOOL finished) {
            
        }];
       
    }
    
}