如何使UIScrollView作为UITableView向上滚动效果

Question

即使内容大小适合设备屏幕大小，我也想像UITableView一样使滚动视图上下滚动。但是，向上滚动后，最终内容大小必须与起始内容大小相同（为零）。有办法吗？

Answer 1

[当用户向下滚动时像UITableView拉伸效果一样，这里有一个代码捕捉跳动效果

    class ScrollViewController: UIScrollViewDelegate {

         private var topViewHeightConstraintConstant: CGFloat = 259
            @IBOutlet weak var TopViewHeightConstraint: NSLayoutConstraint!


                func scrollViewDidScroll(_ scrollView: UIScrollView) {
                    if scrollView === self.scrollView {
                        if scrollView.isBouncingBottom || scrollView.contentOffset.y >= scrollView.contentSize.height - scrollView.frame.size.height {
                            scrollView.setContentOffset(CGPoint(x: scrollView.contentOffset.x, y: scrollView.contentSize.height - scrollView.frame.size.height), animated: false)
                        }
                        else if  scrollView.isBouncingTop && self.TopViewHeightConstraint.constant ==  topViewHeightConstraintConstant {
                            scrollView.setContentOffset(CGPoint(x: scrollView.contentOffset.x, y: 0), animated: false)
                        }
                        if scrollView.contentOffset.y < 0 {
                            if self.TopViewHeightConstraint.constant + abs(scrollView.contentOffset.y) <= topViewHeightConstraintConstant {
                                self.TopViewHeightConstraint.constant += abs(scrollView.contentOffset.y)
                            }
                        } else if scrollView.contentOffset.y > 0 &&  self.TopViewHeightConstraint.constant >=
                            (self.view.frame.height - self.view.safeAreaInsets.top - self.view.safeAreaInsets.bottom - self.contentViewHeight.constant) {
                            self.TopViewHeightConstraint.constant -= scrollView.contentOffset.y
                            scrollView.setContentOffset(CGPoint(x: scrollView.contentOffset.x, y: 0), animated: false)
                        }
                        view.layoutIfNeeded()
                    }
                }
            }

            func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
             if scrollView !== self.scrollView {
                  TopViewHeightConstraint.constant = topViewHeightConstraintConstant
                 }
             }
}