Animate between container views with `matchedGeometryEffect`

IdentityTest.swift

import SwiftUI
import PlaygroundSupport

// https://www.hackingwithswift.com/quick-start/swiftui/how-to-synchronize-animations-from-one-view-to-another-with-matchedgeometryeffect

struct AdaptiveStack<Content: View>: View {
  var content: () -> Content
  @Binding var vertical: Bool
  init(vertical: Binding<Bool>, @ViewBuilder content: @escaping () -> Content) {
    _vertical = vertical
    self.content = content
  }
  var body: some View {
    if vertical {
      VStack {
        content()
      }
    } else {
      HStack {
        content()
      }
    }
  }
}

struct ContentView: View {
  @State var vertical = true
  @Namespace private var animation
  
  var body: some View {
    VStack {
      Text("Other")
      AdaptiveStack(vertical: $vertical) {
        Text("Top").matchedGeometryEffect(id: "Top", in: animation)
        Text("Bottom").matchedGeometryEffect(id: "Bottom", in: animation)
      }
      Button("vert: \(vertical.description)") {
        withAnimation(.linear(duration: 0.2)) {
          vertical.toggle()
        }
      }
    }
  }
}

PlaygroundPage.current.setLiveView(ContentView().frame(width: 500.0, height: 500.0))