具有环绕和动态高度的SwiftUI HStack [英] SwiftUI HStack with wrap and dynamic height

问题描述

我具有此视图以在从 SwiftUI HStack获得的多行上显示文本标签使用Wrap ，但是当我将其添加到VStack中时，标记会与我在下面放置的任何其他视图重叠. 标签显示正确，但视图本身的高度未在VStack内部计算. 如何使该视图使用is的高度?

I have this view to show text tags on multiple lines which I got from SwiftUI HStack with Wrap, but when I add it in a VStack the tags overlap any other view that I put below. The tags are shown properly but the height of the view itself is not calculated inside the VStack. How can I make this view use the height of is content?

import SwiftUI

struct TestWrappedLayout: View {
    @State var platforms = ["Ninetendo", "XBox", "PlayStation", "PlayStation 2", "PlayStation 3", "PlayStation 4"]

    var body: some View {
        GeometryReader { geometry in
            self.generateContent(in: geometry)
        }
    }

    private func generateContent(in g: GeometryProxy) -> some View {
        var width = CGFloat.zero
        var height = CGFloat.zero

        return ZStack(alignment: .topLeading) {
            ForEach(self.platforms, id: \.self) { platform in
                self.item(for: platform)
                    .padding([.horizontal, .vertical], 4)
                    .alignmentGuide(.leading, computeValue: { d in
                        if (abs(width - d.width) > g.size.width)
                        {
                            width = 0
                            height -= d.height
                        }
                        let result = width
                        if platform == self.platforms.last! {
                            width = 0 //last item
                        } else {
                            width -= d.width
                        }
                        return result
                    })
                    .alignmentGuide(.top, computeValue: {d in
                        let result = height
                        if platform == self.platforms.last! {
                            height = 0 // last item
                        }
                        return result
                    })
            }
        }
    }

    func item(for text: String) -> some View {
        Text(text)
            .padding(.all, 5)
            .font(.body)
            .background(Color.blue)
            .foregroundColor(Color.white)
            .cornerRadius(5)
    }
}

struct TestWrappedLayout_Previews: PreviewProvider {
    static var previews: some View {
        TestWrappedLayout()
    }
}

示例代码:

struct ExampleTagsView: View {
    var body: some View {
        ScrollView {
            VStack(alignment: .leading) {
                Text("Platforms:")
                TestWrappedLayout()

                Text("Other Platforms:")
                TestWrappedLayout()
            }
        }
    }
}

struct ExampleTagsView_Previews: PreviewProvider {
    static var previews: some View {
        ExampleTagsView()
    }
}

结果:

推荐答案

好，这是更通用的&改进的变体(用于最初在带有Wrap的SwiftUI HStack 中引入的解决方案)

Ok, here is a bit more generic & improved variant (for the solution initially introduced in SwiftUI HStack with Wrap)

通过Xcode 11.4/iOS 13.4测试

Tested with Xcode 11.4 / iOS 13.4

注意:由于视图高度是动态计算的，因此结果在运行时有效，而不在预览中有效

struct TagCloudView: View {
    var tags: [String]

    @State private var totalHeight 
          = CGFloat.zero       // << variant for ScrollView/List
    //    = CGFloat.infinity   // << variant for VStack

    var body: some View {
        VStack {
            GeometryReader { geometry in
                self.generateContent(in: geometry)
            }
        }
        .frame(height: totalHeight)// << variant for ScrollView/List
        //.frame(maxHeight: totalHeight) // << variant for VStack
    }

    private func generateContent(in g: GeometryProxy) -> some View {
        var width = CGFloat.zero
        var height = CGFloat.zero

        return ZStack(alignment: .topLeading) {
            ForEach(self.tags, id: \.self) { tag in
                self.item(for: tag)
                    .padding([.horizontal, .vertical], 4)
                    .alignmentGuide(.leading, computeValue: { d in
                        if (abs(width - d.width) > g.size.width)
                        {
                            width = 0
                            height -= d.height
                        }
                        let result = width
                        if tag == self.tags.last! {
                            width = 0 //last item
                        } else {
                            width -= d.width
                        }
                        return result
                    })
                    .alignmentGuide(.top, computeValue: {d in
                        let result = height
                        if tag == self.tags.last! {
                            height = 0 // last item
                        }
                        return result
                    })
            }
        }.background(viewHeightReader($totalHeight))
    }

    private func item(for text: String) -> some View {
        Text(text)
            .padding(.all, 5)
            .font(.body)
            .background(Color.blue)
            .foregroundColor(Color.white)
            .cornerRadius(5)
    }

    private func viewHeightReader(_ binding: Binding<CGFloat>) -> some View {
        return GeometryReader { geometry -> Color in
            let rect = geometry.frame(in: .local)
            DispatchQueue.main.async {
                binding.wrappedValue = rect.size.height
            }
            return .clear
        }
    }
}

struct TestTagCloudView : View {
    var body: some View {
        VStack {
            Text("Header").font(.largeTitle)
            TagCloudView(tags: ["Ninetendo", "XBox", "PlayStation", "PlayStation 2", "PlayStation 3", "PlayStation 4"])
            Text("Some other text")
            Divider()
            Text("Some other cloud")
            TagCloudView(tags: ["Apple", "Google", "Amazon", "Microsoft", "Oracle", "Facebook"])
        }
    }
}

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