如何使SwiftUI视图扩展至UIHostingController的容器尺寸？

在UIKit ViewController中使用UIHostingController嵌入SwiftUI视图FeatureIntroductionView，已将UIHostingController的frame设置为与ViewController中的backgroundImageView一致，但SwiftUI视图未能填充UIHostingController的空间。

SwiftUI视图代码

struct FeatureIntroductionView: View {

let image: String
let title: String
let subtitle: String
let buttonTitle: String

var body: some View {
    VStack(spacing: 33) {
        Image(image)
        VStack(alignment: .center, spacing: 4) {
            Text(title)
                .foregroundColor(.white)
                .font(Font(UIFont.boldFontWith(size: 28)))
                
            Text(subtitle)
                .foregroundColor(.white)
                .font(Font(UIFont.regularFontWith(size: 16)))
                .multilineTextAlignment(.center)

        }
        
        SecondaryButton(title: buttonTitle) {
            // Close
        }
    }
    .padding(48)
    .background(.ultraThinMaterial,
                in: Rectangle())
    .frame(maxWidth: .infinity, maxHeight: .infinity)

}

UIViewController嵌入代码

func addIntroductoryView() {
    let swipeFeatureIntroductionView = FeatureIntroductionView(image: "Swipe",
                                                               title: "Swipe to change",
                                                               subtitle: "Switch between quotes by swiping gesture or tapping on the screen.",
                                                               buttonTitle: "Got it")

    var swipeFeatureIntroductionHostingController = UIHostingController(rootView: swipeFeatureIntroductionView)
    swipeFeatureIntroductionHostingController.view.invalidateIntrinsicContentSize()
    addChild(swipeFeatureIntroductionHostingController)
    swipeFeatureIntroductionHostingController.view.frame = backgroundImageView.frame
    swipeFeatureIntroductionHostingController.view.layer.cornerRadius = 16
    swipeFeatureIntroductionHostingController.view?.clipsToBounds = true
    swipeFeatureIntroductionHostingController.view.backgroundColor = .clear
    view.addSubview(swipeFeatureIntroductionHostingController.view)
    swipeFeatureIntroductionHostingController.didMove(toParent: self)
}

1. 修改SwiftUI视图，确保背景填充整个可用空间 #

原代码中.background(.ultraThinMaterial, in: Rectangle())的Rectangle仅适配内部VStack的大小，而非整个UIHostingController的空间。调整修饰符顺序并简化背景设置：

struct FeatureIntroductionView: View {
    let image: String
    let title: String
    let subtitle: String
    let buttonTitle: String

    var body: some View {
        VStack(spacing: 33) {
            Image(image)
            VStack(alignment: .center, spacing: 4) {
                Text(title)
                    .foregroundColor(.white)
                    .font(Font(UIFont.boldFontWith(size: 28)))
                
                Text(subtitle)
                    .foregroundColor(.white)
                    .font(Font(UIFont.regularFontWith(size: 16)))
                    .multilineTextAlignment(.center)
            }
            
            SecondaryButton(title: buttonTitle) {
                // Close
            }
        }
        .padding(48)
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(.ultraThinMaterial)
    }
}

• 调整修饰符顺序：先通过frame(maxWidth: .infinity, maxHeight: .infinity)让根视图占满所有可用空间，再添加背景，确保背景覆盖整个视图范围。
• 移除in: Rectangle()：直接使用.background(.ultraThinMaterial)会自动填充当前视图的全部区域，无需手动指定形状。

2. 优化UIHostingController的嵌入逻辑 #

原代码中直接设置frame并调用invalidateIntrinsicContentSize()可能导致布局冲突，改用AutoLayout约束替代硬编码frame：

func addIntroductoryView() {
    let swipeFeatureIntroductionView = FeatureIntroductionView(image: "Swipe",
                                                               title: "Swipe to change",
                                                               subtitle: "Switch between quotes by swiping gesture or tapping on the screen.",
                                                               buttonTitle: "Got it")

    let swipeFeatureIntroductionHostingController = UIHostingController(rootView: swipeFeatureIntroductionView)
    addChild(swipeFeatureIntroductionHostingController)
    
    // 关闭自动转换约束，手动添加约束
    swipeFeatureIntroductionHostingController.view.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(swipeFeatureIntroductionHostingController.view)
    
    // 添加与backgroundImageView完全重合的约束
    NSLayoutConstraint.activate([
        swipeFeatureIntroductionHostingController.view.topAnchor.constraint(equalTo: backgroundImageView.topAnchor),
        swipeFeatureIntroductionHostingController.view.leadingAnchor.constraint(equalTo: backgroundImageView.leadingAnchor),
        swipeFeatureIntroductionHostingController.view.trailingAnchor.constraint(equalTo: backgroundImageView.trailingAnchor),
        swipeFeatureIntroductionHostingController.view.bottomAnchor.constraint(equalTo: backgroundImageView.bottomAnchor)
    ])
    
    swipeFeatureIntroductionHostingController.view.layer.cornerRadius = 16
    swipeFeatureIntroductionHostingController.view.clipsToBounds = true
    swipeFeatureIntroductionHostingController.view.backgroundColor = .clear
    
    swipeFeatureIntroductionHostingController.didMove(toParent: self)
}

• 移除invalidateIntrinsicContentSize()：该方法会强制UIHostingController重新计算内在大小，可能破坏填充布局。
• 使用AutoLayout约束：相比直接设置frame，约束能确保在视图大小变化（如屏幕旋转）时，UIHostingController始终与backgroundImageView保持一致的尺寸。

内容的提问来源于stack exchange，提问作者haven-way