FB7671513.md

FB7671513

If you run the code below in a playground you will see that tapping the buttons doesn’t change the UI.

However, if you move the GeometryReader to the outside of ViewModelView it will begin working again.

import SwiftUI
import PlaygroundSupport

class ViewModel: ObservableObject {
  @Published var count = 0
}

struct ViewModelView<Content: View>: View {
  @ObservedObject var viewModel = ViewModel()

  let content: (ViewModel) -> Content

  init(@ViewBuilder content: @escaping (ViewModel) -> Content) {
    self.content = content
  }

  var body: some View {
    // move the geometry reader to here to get it working
    // GeometryReader { proxy in 
    self.content(self.viewModel)
    // }
  }
}

let v = ViewModelView { viewModel in
  GeometryReader { proxy in
    HStack {
      Button("-") { viewModel.count -= 1 }
      Text("\(viewModel.count)")
      Button("+") { viewModel.count += 1 }
    }
  }
}

PlaygroundPage.current.setLiveView(v)

The same happens with ScrollViewReader.