Created
August 6, 2022 08:11
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Comparing custom HStack with default HStack
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| //: A UIKit based Playground for presenting user interface | |
| import SwiftUI | |
| import PlaygroundSupport | |
| struct MyEqualWidthHStack: Layout { | |
| /// Returns a size that the layout container needs to arrange its subviews | |
| /// horizontally. | |
| /// - Tag: sizeThatFitsHorizontal | |
| func sizeThatFits( | |
| proposal: ProposedViewSize, | |
| subviews: Subviews, | |
| cache: inout Void | |
| ) -> CGSize { | |
| guard !subviews.isEmpty else { return .zero } | |
| let maxSize = maxSize(subviews: subviews) | |
| let spacing = spacing(subviews: subviews) | |
| let totalSpacing = spacing.reduce(0) { $0 + $1 } | |
| return CGSize( | |
| width: maxSize.width * CGFloat(subviews.count) + totalSpacing, | |
| height: maxSize.height) | |
| } | |
| /// Places the subviews in a horizontal stack. | |
| /// - Tag: placeSubviewsHorizontal | |
| func placeSubviews( | |
| in bounds: CGRect, | |
| proposal: ProposedViewSize, | |
| subviews: Subviews, | |
| cache: inout Void | |
| ) { | |
| guard !subviews.isEmpty else { return } | |
| let maxSize = maxSize(subviews: subviews) | |
| let spacing = spacing(subviews: subviews) | |
| let placementProposal = ProposedViewSize(width: maxSize.width, height: maxSize.height) | |
| var nextX = bounds.minX + maxSize.width / 2 | |
| for index in subviews.indices { | |
| subviews[index].place( | |
| at: CGPoint(x: nextX, y: bounds.midY), | |
| anchor: .center, | |
| proposal: placementProposal) | |
| nextX += maxSize.width + spacing[index] | |
| } | |
| } | |
| /// Finds the largest ideal size of the subviews. | |
| private func maxSize(subviews: Subviews) -> CGSize { | |
| let subviewSizes = subviews.map { $0.sizeThatFits(.unspecified) } | |
| let maxSize: CGSize = subviewSizes.reduce(.zero) { currentMax, subviewSize in | |
| CGSize( | |
| width: max(currentMax.width, subviewSize.width), | |
| height: max(currentMax.height, subviewSize.height)) | |
| } | |
| return maxSize | |
| } | |
| /// Gets an array of preferred spacing sizes between subviews in the | |
| /// horizontal dimension. | |
| private func spacing(subviews: Subviews) -> [CGFloat] { | |
| subviews.indices.map { index in | |
| guard index < subviews.count - 1 else { return 0 } | |
| return subviews[index].spacing.distance( | |
| to: subviews[index + 1].spacing, | |
| along: .horizontal) | |
| } | |
| } | |
| } | |
| struct ContentView: View { | |
| var body: some View { | |
| VStack(spacing: 0) { | |
| (MyEqualWidthHStack()) { | |
| Text("Hi") | |
| .frame(maxWidth: .infinity) | |
| .background(.blue) | |
| Text("Hellooooo") | |
| .frame(maxWidth: .infinity) | |
| .background(.green) | |
| Text("World") | |
| .frame(maxWidth: .infinity) | |
| .background(.orange) | |
| } | |
| .padding(.vertical) | |
| .padding(.bottom, 10) | |
| .font(.headline) | |
| Divider() | |
| HStack { | |
| Text("Hi") | |
| .frame(maxWidth: .infinity) | |
| .background(.blue) | |
| Text("Hellooooo") | |
| .frame(maxWidth: .infinity) | |
| .background(.green) | |
| Text("World") | |
| .frame(maxWidth: .infinity) | |
| .background(.orange) | |
| } | |
| .padding(.vertical) | |
| .padding(.bottom, 10) | |
| .font(.headline) | |
| } | |
| .background(.thinMaterial) | |
| } | |
| } | |
| let hostingVc = UIHostingController(rootView: ContentView()) | |
| hostingVc.view.frame = .init(x: 0, y: 0, width: 500, height: 600) | |
| PlaygroundPage.current.liveView = hostingVc |
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