ios - UIHostingController 应该扩展以适应内容

Question

我有一个自定义 UIViewControllerRepresentable (布局相关代码如下所示)。这试图复制原生 SwiftUI ScrollView , 除了它从顶部以外的底部滚动。
查看层次结构

view: UIView
|
\- scrollView: UIScrollView
   |
   \- innerView: UIView
      |
      \- hostingController.view: SwiftUI hosting view

当 View 初始化时，这一切都按预期工作。宿主视图填充了它的内容，并且约束确保 ScrollView 的 contentSize设置正确。
然而，当宿主视图的内容改变时， hostingController.view不会调整大小以适应其内容。

Green: As intended, the scroll view matches the size of the hosting view controller.

Blue: The hosting view itself. It keeps the size it had when it was first loaded, and doesn't expend as it should.

Red: A stack view within the hosting view. In this screenshot, content was been added to the stack, causing it to expand. You can see the difference in size as a result.

UIHostingController(蓝色)应该扩展以适应其内容(红色)。
ScrollView 的内容大小没有明确设置，因为这是由自动布局处理的。
如果有帮助，约束代码如下所示。

class UIBottomScrollViewController<Content: View>: UIViewController, UIScrollViewDelegate {
    var hostingController: UIHostingController<Content>! = nil

    init(rootView: Content) {
        self.hostingController = UIHostingController<Content>(rootView: rootView)
        super.init(nibName: nil, bundle: nil)
    }
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    var scrollView: UIScrollView = UIScrollView()
    var innerView = UIView()

    override func loadView() {
        self.view = UIView()
        self.addChild(hostingController)
        view.addSubview(scrollView)
        scrollView.addSubview(innerView)
        innerView.addSubview(hostingController.view)

        scrollView.delegate = self
        scrollView.scrollsToTop = true
        scrollView.isScrollEnabled = true
        scrollView.clipsToBounds = false

        scrollView.layoutMargins = .zero
        scrollView.preservesSuperviewLayoutMargins = true

        scrollView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        scrollView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true

        innerView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
        innerView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        innerView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        innerView.leftAnchor.constraint(equalTo: scrollView.leftAnchor).isActive = true
        innerView.rightAnchor.constraint(equalTo: scrollView.rightAnchor).isActive = true
        innerView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true


        hostingController.view.topAnchor.constraint(equalTo: innerView.topAnchor).isActive = true
        hostingController.view.leftAnchor.constraint(equalTo: innerView.leftAnchor).isActive = true
        hostingController.view.rightAnchor.constraint(equalTo: innerView.rightAnchor).isActive = true
        hostingController.view.bottomAnchor.constraint(equalTo: innerView.bottomAnchor).isActive = true


        hostingController.view.autoresizingMask = []
        hostingController.view.layoutMargins = .zero
        hostingController.view.insetsLayoutMarginsFromSafeArea = false
        hostingController.view.translatesAutoresizingMaskIntoConstraints = false

        scrollView.autoresizingMask = []
        scrollView.layoutMargins = .zero
        scrollView.insetsLayoutMarginsFromSafeArea = false
        scrollView.translatesAutoresizingMaskIntoConstraints = false

        innerView.autoresizingMask = []
        innerView.layoutMargins = .zero
        innerView.insetsLayoutMarginsFromSafeArea = false
        innerView.translatesAutoresizingMaskIntoConstraints = false

        hostingController.didMove(toParent: self)

        scrollView.keyboardDismissMode = .interactive
    }
}

struct BottomScrollView<Content: View>: UIViewControllerRepresentable {
    var content: () -> Content

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content
    }

    func makeUIViewController(context: Context) -> UIBottomScrollViewController<Content> {
        let vc = UIBottomScrollViewController(rootView: self.content())
        return vc
    }
    func updateUIViewController(_ viewController: UIBottomScrollViewController<Content>, context: Context) {
        viewController.hostingController.rootView = self.content()
    }
}

Answer 1

对我来说，这个解决方案比我在这里看到的任何其他答案都简单得多(没有一个有效)，尽管我花了很长时间才找到它。
我所做的只是创建一个UIHostingController 的瘦子类。调用 invalidateIntrinsicContentSize()对 viewDidLayoutSubviews() 的回应

class SelfSizingHostingController<Content>: UIHostingController<Content> where Content: View {

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        self.view.invalidateIntrinsicContentSize()
    }
}

与原始问题类似，我在 UIViewController 中托管了一个 SwiftUI View 。在 UIScrollView ，需要与滚动内容 View 中的其他 View 一起布局。 SwiftUI View 的固有大小根据其内容和用户选择的动态类型大小而变化。
就我而言，这真的很简单。它适用于 iOS 14+(未在 iOS 13 上测试)，其中 SwiftUI 内容的更改会导致新的内在大小正确更新 ScrollView 中基于自动布局的 UIKit 布局。老实说，这不是 UIHostingController 的隐含行为，这感觉就像一个错误。 .