The following code worked just fine as expected until I threw in an additional Text views write below the Toggle (it is commented out in the code below). When I do that I get a Geometry action is cycling between duplicate values. error and the program eventually hangs (on X86 15.2). It does not really hang but seems stuck in some infinite update loop consuming a 100% of a core and eating up RAM. Same error on M3 15.1 except haven’t been able to make it hang/get stuck yet.

Seems like a new error since Google returns no results for it.

Anyone seen anything like that, if yes, what does it mean?

Is there a problem with the code or is this a sign of a possible bug in SwiftUI?

struct CaptureSizeView: ViewModifier {
  @Binding var size: CGSize

  func body(content: Self.Content) -> some View {
    content
      .onGeometryChange(for: CGSize.self) { proxy in proxy.size }
      action: { newValue in size = newValue }
  }
}

public extension View {
  func captureSize(_ size: Binding<CGSize>) -> some View {
    modifier(CaptureSizeView(size: size))
  }
}

public extension CGSize {
  var aspectRatio: CGFloat { self.width / self.height }
}

struct ContentView: View {
  @State private var clearSize: CGSize = .zero
  @State private var isSquare: Bool = false

  var body: some View {
    HStack(alignment: .top) {
      VStack(alignment: .leading) {
        Toggle("Keep Square", isOn: $isSquare).toggleStyle(.switch)
//  Uncomment: error "Geometry action is cycling between duplicate values."
//        Text("available size: (clearSize)")
      }
      .padding()

      Divider()

      VStack {
        Text("Canvas")
          .font(.largeTitle)
          .fontWeight(.black)
        Text("available size: (clearSize)")

        ZStack {
          Color.clear
            .border(.green)
            .captureSize($clearSize)
            .overlay {
              Canvas { _, _ in
              }
              .aspectRatio(isSquare ? 1 : clearSize.aspectRatio, contentMode: .fit)
              .background(.yellow)
            }
        }
        .padding()
      }
    }
  }
}