如何在包含 ZStacks 的 VStack 上显示视图

Question

我需要一个视图网格，其中每个项目根据网格中项目的数量调整大小，并且我需要在点击时扩展网格的每个项目。

我最终设法根据需要布置项目（见图 1）并展开它们。

不幸的是，我无法使用 zIndex 将展开的项目正确地放在所有其他视图的前面（参见图 2 和图 3）。

我还尝试将 VStack 和 HStack 都嵌入到 ZStack 中，但没有任何变化。

我怎样才能把展开的项目放在上面？

下面是我的代码。

struct ContentViewNew: View {
    private let columns: Int = 6
    private let rows: Int = 4
    @ObservedObject var viewModel: ViewModel
    var cancellables = Set<AnyCancellable>()

    init() {
        viewModel = ViewModel(rows: rows, columns: columns)
        viewModel.objectWillChange.sink { _ in
            print("viewModel Changed")
        }.store(in: &cancellables)
    }

    var body: some View {
        GeometryReader { geometryProxy in

            let hSpacing: CGFloat = 7
            let vSpacing: CGFloat = 7

            let hSize = (geometryProxy.size.width - hSpacing * CGFloat(columns + 1)) / CGFloat(columns)
            let vSize = (geometryProxy.size.height - vSpacing * CGFloat(rows + 1)) / CGFloat(rows)
            let size = min(hSize, vSize)

            VStack {
                ForEach(0 ..< viewModel.rows, id: \.self) { row in
                    Spacer()
                    HStack {
                        Spacer()
                        ForEach(0 ..< viewModel.columns, id: \.self) { column in

                            GeometryReader { widgetProxy in

                                ItemWiew(info: viewModel.getItem(row: row, column: column), size: size, zoomedSize: 0.80 * geometryProxy.size.width)
                                    .offset(x: viewModel.getItem(row: row, column: column).zoomed ? (geometryProxy.size.width / 2.0 - (widgetProxy.frame(in: .global).origin.x + widgetProxy.size.width / 2.0)) : 0,
                                            y: viewModel.getItem(row: row, column: column).zoomed ? geometryProxy.size.height / 2.0 - (widgetProxy.frame(in: .global).origin.y + widgetProxy.size.height / 2.0) : 0)
                                    .onTapGesture {
                                        viewModel.zoom(row: row, column: column)
                                    }
                                    .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
                                    .zIndex(viewModel.getItem(row: row, column: column).zoomed ? 10000 : 0)
                                    .background(Color.gray)
                            }
                            Spacer()
                        }
                    }
                    .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
                    .background(Color.blue)
                    Spacer()
                }
            }
            .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
            .background(Color.yellow)
        }
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
        .background(Color.green)
    }
}

struct ItemWiew: View {
    @ObservedObject var info: ItemInfo
    var size: CGFloat

    init(info: ItemInfo, size: CGFloat, zoomedSize: CGFloat) {
        self.info = info
        self.size = size
        if self.info.size == 0 {
            self.info.size = size
            self.info.zoomedSize = zoomedSize
        }
    }

    var body: some View {
        VStack {
            Print("Drawing Widget with size \(self.info.size)")
            Image(systemName: info.symbol)
                .font(.system(size: 30))
                .frame(width: info.size, height: info.size)
                .background(info.color)
                .cornerRadius(10)
        }
    }
}

class ItemInfo: ObservableObject, Identifiable {
    var symbol: String
    var color: Color
    var zoomed = false
    @Published var size: CGFloat
    @Published var originalSize: CGFloat
    @Published var zoomedSize: CGFloat

    init(symbol: String, color: Color) {
        self.symbol = symbol
        self.color = color
        size = 0.0
        originalSize = 0.0
        zoomedSize = 0.0
    }

    func toggleZoom() {
        if zoomed {
            size = originalSize
            color = .red
        } else {
            size = zoomedSize
            color = .white
        }
        zoomed.toggle()
    }
} 

class ViewModel: ObservableObject {
    private var symbols = ["keyboard", "hifispeaker.fill", "printer.fill", "tv.fill", "desktopcomputer", "headphones", "tv.music.note", "mic", "plus.bubble", "video"]
    private var colors: [Color] = [.yellow, .purple, .green]
    @Published var listData = [ItemInfo]()
    var rows = 0
    var columns = 0

    init(rows: Int, columns: Int) {
        self.rows = rows
        self.columns = columns
        for _ in 0 ..< rows {
            for j in 0 ..< columns {
                listData.append(ItemInfo(symbol: symbols[j % symbols.count], color: colors[j % colors.count]))
            }
        }
    }

    func getItem(row: Int, column: Int) -> ItemInfo {
        return listData[columns * row + column]
    }

    func zoom(row: Int, column: Int) {
        listData[columns * row + column].toggleZoom()
        objectWillChange.send()
    }
}

Answer 1

您发布了很多代码。 我试着把它简化一点。 大多数情况下，您过度使用了 size/zoomedSize/originalSize 属性。

首先，您可以使ItemInfo成为结构并删除所有与大小相关的属性：

struct ItemInfo {
    var symbol: String
    var color: Color

    init(symbol: String, color: Color) {
        self.symbol = symbol
        self.color = color
    }
}

然后通过删除所有与大小相关的属性再次简化您的ViewModel ：

class ViewModel: ObservableObject {
    private var symbols = ["keyboard", "hifispeaker.fill", "printer.fill", "tv.fill", "desktopcomputer", "headphones", "tv.music.note", "mic", "plus.bubble", "video"]
    private var colors: [Color] = [.yellow, .purple, .green]
    @Published var listData = [ItemInfo]()
    let rows: Int
    let columns: Int

    init(rows: Int, columns: Int) {
        self.rows = rows
        self.columns = columns
        for _ in 0 ..< rows {
            for j in 0 ..< columns {
                listData.append(ItemInfo(symbol: symbols[j % symbols.count], color: colors[j % colors.count]))
            }
        }
    }

    func getItem(row: Int, column: Int) -> ItemInfo {
        return listData[columns * row + column]
    }
}

然后更新您的ItemView （再次从外部视图中删除所有与大小相关的属性并直接使用GeometryReader ）：

struct ItemWiew: View {
    let itemInfo: ItemInfo

    var body: some View {
        GeometryReader { proxy in
            self.imageView(proxy: proxy)
        }
    }

    // extracted to another function as you can't use `let` inside a `GeometryReader` closure
    func imageView(proxy: GeometryProxy) -> some View {
        let sideLength = min(proxy.size.width, proxy.size.height) // to make it fill all the space but remain a square
        return Image(systemName: itemInfo.symbol)
            .font(.system(size: 30))
            .frame(maxWidth: sideLength, maxHeight: sideLength)
            .background(itemInfo.color)
            .cornerRadius(10)
    }
}

现在您可以更新ContentView ：

struct ContentView: View {
    private let columns: Int = 6
    private let rows: Int = 4

    @ObservedObject var viewModel: ViewModel

    // zoomed item (nil if no item is zoomed)
    @State var zoomedItem: ItemInfo?

    init() {
        viewModel = ViewModel(rows: rows, columns: columns)
    }

    var body: some View {
        ZStack {
            gridView
            zoomedItemView
        }
    }

    var gridView: some View {
        let spacing: CGFloat = 7
        return VStack(spacing: spacing) {
            ForEach(0 ..< viewModel.rows, id: \.self) { rowIndex in
                self.rowView(rowIndex: rowIndex)
            }
        }
        .padding(.all, spacing)
    }

    func rowView(rowIndex: Int) -> some View {
        let spacing: CGFloat = 7
        return HStack(spacing: spacing) {
            ForEach(0 ..< viewModel.columns, id: \.self) { columnIndex in
                ItemWiew(itemInfo: self.viewModel.getItem(row: rowIndex, column: columnIndex))
                    .onTapGesture {
                        // set zoomed item on tap gesture
                        self.zoomedItem = self.viewModel.getItem(row: rowIndex, column: columnIndex)
                    }
            }
        }
    }
}

最后在zoomedItemView我重用了ItemView但您可以为缩放项目创建一些其他视图：

extension ContentView {
    var zoomedItemView: some View {
        Group {
            if zoomedItem != nil {
                ItemWiew(itemInfo: zoomedItem!)
                    .onTapGesture {
                        self.zoomedItem = nil
                    }
            }
        }
        .padding()
    }
}

注意：为简单起见，我将ItemInfo结构。 如果您不打算在zoomedView内对其进行修改并将更改应用于网格，则建议您这样做。 但是如果由于某种原因你需要它是一个class和一个ObservableObject你可以很容易地恢复你原来的声明：

class ItemInfo: ObservableObject, Identifiable { ... }

未选择项目：

使用缩放项目：