我终于明白了，我希望这更容易理解。

你通常可以通过添加一个基本的UIView到滚动视图作为一个“内容视图”来绕过这个警告，就像他们提到的，让它和你的滚动视图一样大，在这个内容视图上，设置这6个参数。

如您所见，您总共需要6个参数!哪一个在正常情况下，你复制了两个约束，但这是避免故事板错误的方法。

使用contentView (UView)作为容器在UIScrollView，坚持边缘(上，下，后，前)的superview (UIScrollView)和contentView应该有等宽和等高的superview。这些都是约束条件。方法的调用:

-(void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    self.scrollView.contentSize = self.contentView.frame.size;
}

为我解决了问题。

This error took me a while to track down, initially I tried pinning the ScrollView's size but the error message clearly says "content size". I made sure everything I pinned from the top of the ScrollView was also pinned to the bottom. That way the ScrollView can calculate its content height by finding the height of all the objects & constraints. This solved the ambiguous content height, the width is pretty similar... Initially I had most things X centered in the ScrollView, but I had to also pin the objects to the side of the ScrollView. I don't like this because the iPhone6 might have a wider screen but it will remove the 'ambiguous content width' error.

Swift 4+方法:

1)设置UIScrollView的上、下、左、右边缘为0

2)在UIScrollView中添加一个UIView，并设置顶部、底部、前边距和尾随边距为0(等于UIScrollView的边距)。

3)最重要的部分是设置宽度和高度，其中高度约束的优先级应该低。

private func setupConstraints() {

    // Constraints for scrollView
    scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
    scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
    scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true

    // Constraints for containerView
    containerView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
    containerView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
    containerView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true
    containerView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
    containerView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true

    let heightConstraint = containerView.heightAnchor.constraint(equalTo: scrollView.heightAnchor)
    heightConstraint.priority = UILayoutPriority(rawValue: 250)
    heightConstraint.isActive = true
}

我通过使用“解决自动布局问题”>“为所选视图添加缺失约束”来解决我的视图的这种问题

以下两个约束条件可以解决我的问题:

trailing = Stack View.trailing - 10
bottom = Stack View.bottom + 76

中: 尾随，bottom是UIScrollView的尾随，底部

使用自动布局

在一个定义良好的视图中添加滚动视图，然后在滚动视图中添加堆栈视图

从滚动视图和堆栈视图中添加上、左、右、下、中心X和中心Y约束到相关的超级视图中

确保约束从堆栈视图链接到正确的父视图(scrollview)，因为当前默认设置是添加Align Top约束，而不是Top Space约束。