Ios UIHostingController应展开以适应内容

我有一个自定义的

UIViewControllerRepresentable

（与布局相关的代码如下所示）。这将尝试复制本机SwiftUI

ScrollView

，但它从底部（顶部除外）滚动

视图层次结构 当视图初始化时，这一切都可以正常工作。宿主视图将填充其内容，这些约束确保滚动视图的

contentSize

设置正确

但是，当宿主视图的内容更改时，

hostingController.view

不会调整大小以适应其内容

绿色：按预期，滚动视图与宿主视图控制器的大小相匹配

蓝色：宿主视图本身。它保持了第一次加载时的大小，并且不会像应该的那样消耗

红色：宿主视图中的堆栈视图。在这个屏幕截图中，内容被添加到堆栈中，导致堆栈扩展。因此，您可以看到大小的差异

UIHostingController（蓝色）应展开以适合其内容（红色）。 滚动视图的内容大小没有明确设置，因为这是由自动布局处理的

约束代码如下所示（如果有帮助的话）

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()
    }
}

类UIViewController:UIViewController、UIScrollViewDelegate{ var hostingController:UIHostingController！=nil init（rootView:Content）{ self.hostingController=UIHostingController（rootView:rootView） super.init（nibName:nil，bundle:nil） } 必需初始化？（编码器：NSCoder）{ fatalError（“初始化（编码者：）尚未实现”） } var scrollView:UIScrollView=UIScrollView（） var innerView=UIView（） 重写func loadView（）{ self.view=UIView（） self.addChild（主机控制器） view.addSubview（滚动视图） scrollView.addSubview（内部视图） innerView.addSubview（hostingController.view） scrollView.delegate=self scrollView.scrollsToTop=true scrollView.IsCrollenabled=true scrollView.clipsToBounds=false scrollView.layoutMargins=.0 scrollView.PreserveSPerviewLayoutMargins=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=.0 hostingController.view.insetsLayoutMarginsFromSafeArea=false hostingController.view.translatesAutoresizingMaskIntoConstraints=false scrollView.autoresizingMask=[] scrollView.layoutMargins=.0 scrollView.InsettsLayoutMarginsFromSafeArea=false scrollView.TranslatesAutoResizezingMaskintoConstraints=false innerView.autoresizingMask=[] innerView.layoutMargins=.0 innerView.insetsLayoutMarginsFromSafeArea=false innerView.TranslatesAutoResizezingMaskintoConstraints=false hostingController.didMove（toParent:self） scrollView.keyboardDismissMode=.interactive } } 结构底部滚动视图：UIViewControllerRepresentable{ 变量内容：（）->内容 初始化（@ViewBuilder内容：@escaping（）->content）{ self.content=内容 } func makeUIViewController（上下文：context）->UIBottomScrollViewController{ 让vc=UIBottomScrollViewController（rootView:self.content（）） 返回vc } func updateUIViewController（viewController:UIBottomScrollViewController，上下文：上下文）{ viewController.hostingController.rootView=self.content（） } }

---

我在类似的ish视图层次结构中遇到了同样的问题，涉及到

UIHostingController

和滚动视图，并发现了一个难看的漏洞使其正常工作。基本上，我添加了高度约束并手动更新常量：

private var heightConstraint: NSLayoutConstraint?

...

override func viewDidLoad() {
    ...


    heightConstraint = viewHost.view.heightAnchor.constraint(equalToConstant: 0)

    ...
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    // This plays off what @Rengers was saying, but wanted to include my solution that took me a fair amount of time to figure out.

Hopefully save some time

struct SizingView<T: View>: View {
    
    let view: T
    let updateSizeHandler: ((_ size: CGSize) -> Void)
    init(view: T, updateSizeHandler: @escaping (_ size: CGSize) -> Void) {
        self.view = view
        self.updateSizeHandler = updateSizeHandler
    }
    var body: some View {
        view.background(
            GeometryReader { proxy in
                Color.clear
                    .preference(key: SizePreferenceKey.self, value: proxy.size)
            }
        )
        .onPreferenceChange(SizePreferenceKey.self) { preferences in
            updateSizeHandler(preferences)
        }

    }
    
    func size(with view: T, geometry: GeometryProxy) -> T {
        updateSizeHandler?(geometry.size)
        return view
    }
}

private var heightConstraint:NSLayoutConstraint？
...
重写func viewDidLoad（）{
...
heightConstraint=viewHost.view.heightAnchor.constraint（equalToConstant:0）
...
}
重写func viewdilayoutsubviews（）{
super.viewDidLayoutSubviews（）
//这是在重复@Rengers所说的话，但想包括我花了相当长时间才弄明白的解决方案

希望能节省一些时间

struct SizingView:View{
让我们来看一看：T
let updateSizeHandler:（（size:CGSize）->Void）
init（视图：T，updateSizeHandler:@escaping（size:CGSize）->Void）{
self.view=view
self.updateSizeHandler=updateSizeHandler
}
var body：一些观点{
view.background(
GeometryReader{中的代理
颜色。清晰
.preference（键：SizePreferenceKey.self，值：proxy.size）
}
)
.onPreferenceChange（大小）
private var heightConstraint: NSLayoutConstraint?

...

override func viewDidLoad() {
    ...


    heightConstraint = viewHost.view.heightAnchor.constraint(equalToConstant: 0)

    ...
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    // This plays off what @Rengers was saying, but wanted to include my solution that took me a fair amount of time to figure out.

Hopefully save some time

struct SizingView<T: View>: View {
    
    let view: T
    let updateSizeHandler: ((_ size: CGSize) -> Void)
    init(view: T, updateSizeHandler: @escaping (_ size: CGSize) -> Void) {
        self.view = view
        self.updateSizeHandler = updateSizeHandler
    }
    var body: some View {
        view.background(
            GeometryReader { proxy in
                Color.clear
                    .preference(key: SizePreferenceKey.self, value: proxy.size)
            }
        )
        .onPreferenceChange(SizePreferenceKey.self) { preferences in
            updateSizeHandler(preferences)
        }

    }
    
    func size(with view: T, geometry: GeometryProxy) -> T {
        updateSizeHandler?(geometry.size)
        return view
    }
}