LazyGridView how to detect and act on item overflowing screen? - swiftui

Question

I have a grid of items. Each item can expand height. I want to autoscroll when the item is expanded so it doesn't overflow the screen.
I was successful with the following code but I had to revert to a hack.
The idea was to detect when the item is overflowing using a Geometry reader on the item's background. Works wonders.
The issue is that when the view is expanded , the geo reader will update after the condition to check if autoscroll should execute is ran by the dispatcher. Hence my ugly hack.
Wonder what is the proper way ?
import SwiftUI
struct BlocksGridView: View {
private var gridItemLayout = [GridItem(.adaptive(minimum: 300, maximum: .infinity), spacing: 20)]
var body: some View {
ZStack{
ScrollView {
ScrollViewReader { value in
LazyVGrid(columns: gridItemLayout, spacing: 20) {
ForEach((0..<20), id: \.self) {
BlockView(cardID: $0,scrollReader: value).id($0)
}
}
}
.padding(20)
}
}
}
}
struct BlockView : View {
var cardID : Int
var scrollReader : ScrollViewProxy
#State private var isOverflowingScreen = false
#State private var expand = false
var body: some View {
ZStack{
Rectangle()
.foregroundColor(isOverflowingScreen ? Color.blue : Color.green)
.frame(height: expand ? 300 : 135)
.clipShape(Rectangle()).cornerRadius(14)
.overlay(Text(cardID.description))
.background(GeometryReader { geo -> Color in
DispatchQueue.main.async {
if geo.frame(in: .global).maxY > UIScreen.main.bounds.maxY {
isOverflowingScreen = true
} else {
isOverflowingScreen = false
}
}
return Color.clear
})
.onTapGesture {
expand.toggle()
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { // <-- Hack :(
if isOverflowingScreen {
withAnimation{
scrollReader.scrollTo(cardID)
}
}
}
}
}
}
}
struct BlocksGridView_Previews: PreviewProvider {
static var previews: some View {
BlocksGridView()
}
}
Blue items are overflowing ...