swift - 带有换行和动态高度的 SwiftUI HStack

Question

我有这个视图可以在多行上显示文本标签，这些文本标签是从带有 Wrap 的 SwiftUI HStack 获得的，但是当我将它添加到 VStack 中时，标签会与我放在下面的任何其他视图重叠。标签显示正确，但视图本身的高度不在 VStack 内计算。如何让这个视图使用内容的高度？

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：

Answer 1

好的，这里有一个更通用和改进的变体（对于最初在SwiftUI HStack 中引入的解决方案，带有 Wrap）

使用 Xcode 11.4 / iOS 13.4 测试

注意：由于视图高度是动态计算的，因此结果在运行时有效，而不是在预览中

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"])
        }
    }
}

Answer 2

我只是设法通过将 GeometryReader 移动到 ExampleTagsView 并在 .alignmentGuide 中使用 platform.first 而不是 last 来解决这个问题

完整代码：

import SwiftUI

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

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

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

struct TestWrappedLayout: View {
    @State var platforms = ["Ninetendo", "XBox", "PlayStation", "PlayStation 2", "PlayStation 3", "PlayStation 4", "PlayStation 5", "Ni", "Xct5Box", "PlayStatavtion", "PlvayStation 2", "PlayStatiadfon 3", "PlaySdatation 4", "PlaySdtation 5"]
    let geometry: GeometryProxy

    var body: some View {
        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.first! {
                            width = 0 //last item
                        } else {
                            width -= d.width
                        }
                        return result
                    })
                    .alignmentGuide(.top, computeValue: {d in
                        let result = height
                        if platform == self.platforms.first! {
                            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)
    }
}

结果：

Answer 3

我调整了 Asperi 的解决方案以接受任何类型的视图和模型。以为我会在这里分享。我将它添加到GitHub Gist并在此处包含代码。

struct WrappingHStack<Model, V>: View where Model: Hashable, V: View {
    typealias ViewGenerator = (Model) -> V
    
    var models: [Model]
    var viewGenerator: ViewGenerator
    var horizontalSpacing: CGFloat = 2
    var verticalSpacing: CGFloat = 0

    @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 geometry: GeometryProxy) -> some View {
        var width = CGFloat.zero
        var height = CGFloat.zero

        return ZStack(alignment: .topLeading) {
            ForEach(self.models, id: \.self) { models in
                viewGenerator(models)
                    .padding(.horizontal, horizontalSpacing)
                    .padding(.vertical, verticalSpacing)
                    .alignmentGuide(.leading, computeValue: { dimension in
                        if (abs(width - dimension.width) > geometry.size.width)
                        {
                            width = 0
                            height -= dimension.height
                        }
                        let result = width
                        if models == self.models.last! {
                            width = 0 //last item
                        } else {
                            width -= dimension.width
                        }
                        return result
                    })
                    .alignmentGuide(.top, computeValue: {dimension in
                        let result = height
                        if models == self.models.last! {
                            height = 0 // last item
                        }
                        return result
                    })
            }
        }.background(viewHeightReader($totalHeight))
    }

    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
        }
    }
}

Answer 4

您可以使用“fixedSize”将内容包装在一个或两个方向：

  .fixedSize(horizontal: true, vertical: true)