blocks|key|745807|text|我在iOS+11上尝试了西蒙·李的答案。它工作得很好，但不是很好。两个滚动视图是同步的，但使用他的方法，滚动视图将失去惯性效果(当您松开手指后继续滚动时)和反弹效果。我认为这是因为通过setContentOffset(offset,+animated:+false)方法设置contentOffset会导致循环调用scrollViewDidScroll(_+scrollView:+UIScrollView)委托的方法(请参阅this+question)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|745808|以下是我在iOS+11上使用的解决方案：|745809|+//+implement+UIScrollViewDelegate+method
++++func+scrollViewDidScroll(_+scrollView:+UIScrollView)+{
++++++++if+scrollView+==+self.scrollViewA+{
++++++++++++self.syncScrollView(self.scrollViewB,+toScrollView:+self.scrollViewA)
++++++++}
++++++++else+if+scrollView+==+self.scrollViewB+{
++++++++++++self.syncScrollView(self.scrollViewA,+toScrollView:+scrollViewB)
++++++++}
++++}

++++func+syncScrollView(_+scrollViewToScroll:+UIScrollView,+toScrollView+scrolledView:+UIScrollView)+{
++++++++var+scrollBounds+=+scrollViewToScroll.bounds
++++++++scrollBounds.origin.y+=+scrolledView.contentOffset.y
++++++++scrollViewToScroll.bounds+=+scrollBounds
++++}|code-block|syntax|javascript|745810|因此，我们使用bounds属性来同步另一个scrollView和用户滚动的那个，而不是设置contentOffset。这样，委托方法scrollViewDidScroll(_+scrollView:+UIScrollView)不会被循环调用，滚动发生得非常流畅，具有惯性和弹跳效果，就像单个滚动视图一样。|745811|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/9418311/setting-contentoffset-programmatically-triggers-scrollviewdidscroll^0|2K|15|3T|D|4D|1B|5X|D|0|0|0|0|7|6|19|D|1U|1B|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|6|7|16|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|17|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

I tried the Simon Lee's answer on iOS 11. It worked but not very well. The two scroll views was synchronized, but using his method, the scroll views would lost the inertia effect(when it continue to scroll after you release your finger) and the bouncing effect. I think it was due to the fact that setting the <code>contentOffset</code> through <code>setContentOffset(offset, animated: false)</code> method causes cyclic calls of the <code>scrollViewDidScroll(_ scrollView: UIScrollView)</code> delegate's method(see <a href="https://stackoverflow.com/questions/9418311/setting-contentoffset-programmatically-triggers-scrollviewdidscroll">this question</a>) 

Here is the solution that worked for me on iOS 11:

<pre><code> // implement UIScrollViewDelegate method
 func scrollViewDidScroll(_ scrollView: UIScrollView) {
 if scrollView == self.scrollViewA {
 self.syncScrollView(self.scrollViewB, toScrollView: self.scrollViewA)
 }
 else if scrollView == self.scrollViewB {
 self.syncScrollView(self.scrollViewA, toScrollView: scrollViewB)
 }
 }

 func syncScrollView(_ scrollViewToScroll: UIScrollView, toScrollView scrolledView: UIScrollView) {
 var scrollBounds = scrollViewToScroll.bounds
 scrollBounds.origin.y = scrolledView.contentOffset.y
 scrollViewToScroll.bounds = scrollBounds
 }
</code></pre>

So instead of setting <code>contentOffset</code> we are using <code>bounds</code> property to sync the other scrollView with the one that was scrolled by the user. This way the delegate method <code>scrollViewDidScroll(_ scrollView: UIScrollView)</code> is not called cyclically and the scrolling happens very smooth and with inertia and bouncing effects as with a single scroll view.

blocks|key|529457|text|伙计们，我知道这个问题已经得到了回答，但我决定在这里与你们分享我解决类似问题的方法，因为我相信这是一个相当干净的解决方案。基本上，我必须让三个集合视图一起滚动，我所做的是做了一个custom+UICollectionView+subclass+called+SharedOffsetCollectionView，当你在故事板中将这个类设置为一个集合视图，或者你直接从代码中实例化它时，你可以让所有的实例滚动相同。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|529458|因此，使用SharedOffsetCollectionView时，应用程序中此类的所有集合视图实例都将始终滚动。在我看来，这是一个干净的解决方案，因为它需要在视图控制器中添加零逻辑，所有这些都包含在这个外部类中，您只需将集合视图的类设置为SharedOffsetCollectionView，就完成了。|529459|同样的方法可以很容易地转移到UITableView和UIScrollView|529460|希望这能对你有所帮助。:)|529461|我的解决方案是这样写的：|529462|Swift+5.2，XCode+11.4.1|529463|entityMap|0|LINK|mutability|MUTABLE|url|https://gist.github.com/stoqn4opm/6d2f8bc765a515a5cc3d81e4a4cbceab^0|2O|G|3L|Q|2H|1U|0|0|5|Q|3B|Q|0|E|B|Q|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@$9|12|A|13|1|14]]|E|$]]|$1|F|3|G|5|6|7|15|8|@$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|1F|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|1G|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|1H|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|Q|$R|$5|S|T|U|E|$V|W]]]]

Guys i know the question is answered, but decided to share with you here my approach for solving a similar issue that i had, because i believe it is a pretty clean solution. Basically i had to make three collection views scroll together, and what i did, is i made a <a href="https://gist.github.com/stoqn4opm/6d2f8bc765a515a5cc3d81e4a4cbceab" rel="nofollow noreferrer">custom <code>UICollectionView</code> subclass called <code>SharedOffsetCollectionView</code></a>, that when you set this class to a collection view in storyboards or you instantiate it from code directly, you can have all instances scroll the same.

So with <code>SharedOffsetCollectionView</code> all collection view instances of this class in your app, will scroll the same always. In my opinion it is a clean solution because it requires adding zero logic in your view controllers, it is all contained in this external class, you just have to set the class of your collection view to be <code>SharedOffsetCollectionView</code> and you are done.

The same approach could easily be transferred to <code>UITableView</code>s and <code>UIScrollView</code>s

Hope that is helpful to some you. :)

My solution is written in:

<h1>Swift 5.2, XCode 11.4.1</h1>

blocks|key|745957|text|上面的答案对我来说并不是很有效，因为我遇到了scrollViewDidScroll的循环调用。这种情况会发生，因为设置滚动视图的内容偏移量也会调用scrollViewDidScoll。我通过在它之间设置一个锁来解决这个问题，这个锁是根据用户是否正在拖动滚动视图来设置的，所以同步不会通过设置内容偏移量来发生：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|745958|func+scrollViewDidScroll(_+scrollView:+UIScrollView)+{
++++self.synchronizeScrollView(offSet:+scrollView.contentOffset.y,
+++++++++++++++++++++++++++++++scrollViewAIsScrolling:+scrollView+==+scrollViewA,
+++++++++++++++++++++++++++++++isScroller:+scrollView.isDragging)
}

private+enum+Scroller+{
++++case+page,+time
}

private+var+scroller:+Scroller?+=+nil

func+synchronizeScrollView(offSet:+CGFloat,+scrollViewAIsScrolling:+Bool,
+++++++++++++++++++++++++++isScroller:+scrollView.isDragging)+{
++++
++++let+scrollViewToScroll+=+scrollViewAIsScrolling+?+scrollViewB+:+scrollViewA
++++var+offset+=+scrollViewToScroll.contentOffset
++++offset.y+=+offSet
++++scrollViewToScroll.setContentOffset(offset,+animated:+false)
}|code-block|syntax|javascript|745959|这段代码可以根据使用的滚动视图数量和拥有它们的人进行重构。我不推荐将一个控制器作为许多滚动视图的代理。我宁愿用委派来解决它。|745960|entityMap^0|M|J|21|I|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

The answer above all did not quite work our for me, since I run into a cyclic call of <code>scrollViewDidScroll</code>. This happend, because setting the content offset of a scroll view also calls <code>scrollViewDidScoll</code>. I solved it by putting a lock between it, which is set based on if a scroll view is being dragged by the user or not, so the syncing won't happen by setting the content offset:
<pre><code>func scrollViewDidScroll(_ scrollView: UIScrollView) {
 self.synchronizeScrollView(offSet: scrollView.contentOffset.y,
 scrollViewAIsScrolling: scrollView == scrollViewA,
 isScroller: scrollView.isDragging)
}

private enum Scroller {
 case page, time
}

private var scroller: Scroller? = nil

func synchronizeScrollView(offSet: CGFloat, scrollViewAIsScrolling: Bool,
 isScroller: scrollView.isDragging) {
 
 let scrollViewToScroll = scrollViewAIsScrolling ? scrollViewB : scrollViewA
 var offset = scrollViewToScroll.contentOffset
 offset.y = offSet
 scrollViewToScroll.setContentOffset(offset, animated: false)
}
</code></pre>
This code can be refactored based on how many scroll views are used and based on who owns them. I won't recommend having one controller being the delegate of many scroll views. I would rather solve it with delegation.

How would I make two scroll views follow each others scrolling? 

For instance, I have a scroll view (A) on the left of a screen, whose contents can scroll up and down, but not left and right. Scroll view B matches the up and down of A, but can also scroll left and right. Scroll view A is always on the screen.

<pre><code>-----------------------------------------------------------
| | |
| | |
| | |
| A | B |
| | |
| scrolls | |
| up &amp; down | scrolls all directions |
| | |
-----------------------------------------------------------
</code></pre>

How would I make it so the the up and down scrolling (of either view) also makes the other view scroll in the same up-down direction? Or is there another method to do this?

Making two UIScrollViews follow each others scrolling

Swift

如何让两个滚动视图彼此滚动？例如，我在屏幕的左侧有一个滚动视图(A)，它的内容可以上下滚动，但不能左右滚动。滚动视图B匹配A的上下滚动，但也可以向左和向右滚动。滚动视图A始终显示在屏幕上。-----------------------------------------------------------|      ...

问让两个UIScrollViews相互跟随滚动
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