HFStretchableTableHeaderView可伸缩TableHeaderView

HFStretchableTableHeaderView 实现了可伸缩的 TableHeaderView

使用方法：

- (void)viewDidLoad
{
    [super viewDidLoad];

    _stretchableTableHeaderView = [HFStretchableTableHeaderView new];
    [_stretchableTableHeaderView stretchHeaderForTableView:self.tableView withView:_stretchView];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    [_stretchableTableHeaderView scrollViewDidScroll:scrollView];
}

- (void)viewDidLayoutSubviews
{
    [_stretchableTableHeaderView resizeView];
}