返回导航到根视图控制器后，折叠的大标题导航栏变得展开

Posted 2023-03-04

【中文标题】返回导航到根视图控制器后，折叠的大标题导航栏变得展开

【英文标题】：Collapsed large title navigation bar becomes expanded after back navigation to root view controller

【发布时间】：2020-12-03 18:30:11

【问题描述】：

我有 UIViewController 和垂直 UIScrollView，它有 UIView 作为它所有子视图的容器。这是我的 scrollView 和 contentView 约束：

        scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        scrollView.widthAnchor.constraint(equalTo: view.safeAreaLayoutGuide.widthAnchor).isActive = true
        scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        
        contentView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor).isActive = true
        contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
        contentView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
        contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true

当我向下滚动时，我的导航栏会变小：

然后我单击 tableviewcell，导航到 detailVC 并返回。这就是问题所在。不知何故，我的导航栏变大了，直到我向任何方向滚动它，然后它跳到正常状态。为什么会发生这种情况，可能是什么原因？

Here 是我的 ViewController 代码的要点

谢谢！

【参考方案1】：

我配置了我的约束并修复了这个问题。

新约束：

        scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        scrollView.widthAnchor.constraint(equalTo: view.safeAreaLayoutGuide.widthAnchor).isActive = true
        
        scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        
        contentView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
        contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true
        contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
        contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
       // contentView.heightAnchor.constraint(equalTo: scrollView.heightAnchor).isActive = would be true if horizontal
        contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true