以编程方式将滚动视图滚动到其底部

Question

我有一个滚动视图，并试图以编程方式滚动到其底部。

尝试了这些：

extension UIScrollView {
// Bonus: Scroll to bottom
func scrollToBottom() {
let bottomOffset = CGPoint(x: 0, y: contentSize.height - bounds.size.height + contentInset.bottom)
if(bottomOffset.y > 0) {
setContentOffset(bottomOffset, animated: true)
}
}
}

从：

在Swift 中以编程方式将 UIScrollView 滚动到子 UIView (子视图( 的顶部

let bottomOffset = CGPoint(x: 0, y: scrollView.contentSize.height - scrollView.bounds.size.height)
scrollView.setContentOffset(bottomOffset, animated: true)

从：

UIScrollView 以编程方式滚动到底部

但两人都什么也没做...

怎么办？

Answer 1

这是滚动到滚动视图的任何特定子级、滚动视图顶部或滚动视图底部的代码。

只需将扩展代码添加到公共类中，然后从需要的地方调用它。

extension UIScrollView {
// Scroll to a specific view so that it's top is at the top our scrollview
func scrollToView(view:UIView, animated: Bool) {
if let origin = view.superview {
// Get the Y position of your child view
let childStartPoint = origin.convertPoint(view.frame.origin, toView: self)
// Scroll to a rectangle starting at the Y of your subview, with a height of the scrollview
self.scrollRectToVisible(CGRect(x:0, y:childStartPoint.y,width: 1,height: self.frame.height), animated: animated)
}
}
// Bonus: Scroll to top
func scrollToTop(animated: Bool) {
let topOffset = CGPoint(x: 0, y: -contentInset.top)
setContentOffset(topOffset, animated: animated)
}
// Bonus: Scroll to bottom
func scrollToBottom() {
let bottomOffset = CGPoint(x: 0, y: contentSize.height - bounds.size.height + contentInset.bottom)
if(bottomOffset.y > 0) {
setContentOffset(bottomOffset, animated: true)
}
}
}

Answer 2

偏移量设置不起作用，因为您在生命周期的早期尝试调用。

您可以尝试在viewDidLayoutSubviews或viewDidAppear更新contentOffset

let bottomOffset = CGPoint(x: 0, y: scrollView.contentSize.height - scrollView.bounds.size.height)
scrollView.setContentOffset(bottomOffset, animated: true)

Answer 3

使用 UIScrollView 的这段代码滚动或从底部开始：

let point = CGPoint(x: 0, y: self.view.frame.size.height) 
scrollView.contentOffset = point

Answer 4

将此代码作为扩展添加到 scrollView

func scrollToBottom(animated: Bool = true) {
let bottomOffset = CGPoint(x: 0, y: self.contentSize.height - self.bounds.size.height)
self.setContentOffset(bottomOffset, animated: true)
}