分页滚动视图约束布局问题

Question

在项目中，我根据约束创建了分页滚动视图。大部分视图是在xib中设置的(SlideViewController.和UIView的SlideView子类将添加到滚动视图中(。SlideViewController 包含 UIScrollView 和 UIView 作为内容视图，该内容视图绑定到具有约束的滚动视图。在 xib 中，这是简单的设置。 当我尝试将多个幻灯片视图添加到内容视图时出现问题。当然，我想添加带有约束的它。首先，它抛出带有详细信息的警告Unable to simultaneously satisfy constraints.：

"<NSLayoutConstraint:0x600001806b70 H:|-(0)-[UIView:0x7ffac0d0cb40]   (active, names: '|':UIScrollView:0x7ffac1842600 )>",
"<NSLayoutConstraint:0x600001806d00 UIView:0x7ffac0d0cb40.centerX == UIScrollView:0x7ffac1842600.centerX   (active)>",
"<NSLayoutConstraint:0x600001805400 UIScrollView:0x7ffac1842600.trailing == UILayoutGuide:0x6000002308c0'UIViewSafeAreaLayoutGuide'.trailing   (active)>",
"<NSLayoutConstraint:0x6000018058b0 UIScrollView:0x7ffac1842600.leading == UILayoutGuide:0x6000002308c0'UIViewSafeAreaLayoutGuide'.leading   (active)>",
"<NSLayoutConstraint:0x6000018065d0 H:|-(0)-[PagingScrollView.SlideView:0x7ffac380be10](LTR)   (active, names: '|':UIView:0x7ffac0d0cb40 )>",
"<NSLayoutConstraint:0x600001806670 PagingScrollView.SlideView:0x7ffac380be10.width == UIScrollView:0x7ffac1842600.width   (active)>",
"<NSLayoutConstraint:0x600001806760 H:[PagingScrollView.SlideView:0x7ffac380be10]-(0)-[PagingScrollView.SlideView:0x7ffac3814d10](LTR)   (active)>",
"<NSLayoutConstraint:0x600001806ad0 PagingScrollView.SlideView:0x7ffac3814d10.width == UIScrollView:0x7ffac1842600.width   (active)>",
"<NSLayoutConstraint:0x600001806d50 H:[PagingScrollView.SlideView:0x7ffac3814d10]-(0)-[PagingScrollView.SlideView:0x7ffac3805d20](LTR)   (active)>",
"<NSLayoutConstraint:0x600001806e90 PagingScrollView.SlideView:0x7ffac3805d20.width == UIScrollView:0x7ffac1842600.width   (active)>",
"<NSLayoutConstraint:0x6000018070c0 H:[PagingScrollView.SlideView:0x7ffac3805d20]-(0)-[PagingScrollView.SlideView:0x7ffac3801b10](LTR)   (active)>",
"<NSLayoutConstraint:0x600001807200 PagingScrollView.SlideView:0x7ffac3801b10.width == UIScrollView:0x7ffac1842600.width   (active)>",
"<NSLayoutConstraint:0x6000018072f0 PagingScrollView.SlideView:0x7ffac3801b10.right == UIView:0x7ffac0d0cb40.right   (active)>",
"<NSLayoutConstraint:0x600001818ff0 'UIView-Encapsulated-Layout-Width' UIView:0x7ffac0d0fba0.width == 414   (active)>",
"<NSLayoutConstraint:0x600001804460 'UIViewSafeAreaLayoutGuide-left' H:|-(0)-[UILayoutGuide:0x6000002308c0'UIViewSafeAreaLayoutGuide'](LTR)   (active, names: '|':UIView:0x7ffac0d0fba0 )>",
"<NSLayoutConstraint:0x600001805130 'UIViewSafeAreaLayoutGuide-right' H:[UILayoutGuide:0x6000002308c0'UIViewSafeAreaLayoutGuide']-(0)-|(LTR)   (active, names: '|':UIView:0x7ffac0d0fba0 )>"

而且它根本不滚动。仅显示最后一个幻灯片视图。看起来内容视图没有根据约束调整大小。

以下代码负责将每个幻灯片视图添加到滚动视图(精确到内容视图(：

private func setup() {
var prevLeftAnchor = contentView.leftAnchor;
for i in 0 ..< slides.count {
slides[i].translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(slides[i])
slides[i].leftAnchor.constraint(equalTo: prevLeftAnchor).isActive = true
slides[i].topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
slides[i].widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
slides[i].heightAnchor.constraint(equalTo: scrollView.heightAnchor).isActive = true
prevLeftAnchor = slides[i].rightAnchor;
}
slides.last?.rightAnchor.constraint(equalTo: contentView.rightAnchor).isActive = true;
}

几个小时后，我卡住了，看不到问题出在哪里。我感谢任何回应。

你可以在github中查看简单的项目 https://github.com/sumofighter666/PageScroller

Answer 1

在你的SlideViewController.xib中，你对Content View有一个CenterX约束......

删除该约束，您应该能够滚动。

请注意，您还有两个Leading约束。由于它们是相同的，因此不会影响任何内容，但为了清楚起见，不妨删除其中一个。