So far it outputs the frames of the cells, but I am stuck trying to hide the ones that are outside of the widget

ContentView.swift

import SwiftUI

struct RegularEventCell: View {
	
	let color: Color
	let title: String
	let description: String?
	
	var body: some View {
		
		HStack {
			
			color.frame(width: 3)
			
			VStack (alignment: .leading, spacing: 0) {
				
				Text(title)
					.font(.caption)
				
				if let desc = description
				{
					Text(desc)
						.font(.caption2)
						.foregroundColor(.secondary)
				}
			}
			
			Spacer()
		}
		.padding([.leading, .trailing], 10)
		.padding([.bottom, .top], 5)
	}
}

extension View {
  func readFrame(onChange: @escaping (CGRect) -> Void) -> some View {
	background(
	  GeometryReader { geometryProxy in
		Color.clear.onAppear() {
			print(geometryProxy.frame(in: .global))
		}
		.preference(key: FramePreferenceKey.self, value: geometryProxy.frame(in: .global))
	  }
	)
	.onPreferenceChange(FramePreferenceKey.self, perform: onChange)
  }
}

private struct FramePreferenceKey: PreferenceKey {
  static var defaultValue: CGRect = .zero
  static func reduce(value: inout CGRect, nextValue: () -> CGRect) {}
}


struct ModelRow: Identifiable {
	let id: String = NSUUID().uuidString
	let title: String
	let description: String?
}

let rows = [ModelRow(title: "One", description: "First"),
			ModelRow(title: "Two", description: nil),
			ModelRow(title: "Three", description: "Third"),
			ModelRow(title: "Four", description: nil),
			ModelRow(title: "Five", description: "Fifth"),
			ModelRow(title: "Six", description: nil)]

struct ContentView : View {

	@State var hiddenCells =  Set<String>()
	
	var body: some View {
		
		let content = GeometryReader { geometry in // causes VStack to be same size as widget
			
			VStack(alignment: .leading, spacing: 1) {
				
				ForEach(rows) { row in
					
					Group {
						
						RegularEventCell(color: .red, title: row.title, description: row.description).readFrame { frame in
							
							if frame.maxY > geometry.size.height
							{
								hiddenCells.insert(row.id)
							}
						}
						Divider()
					}
					.opacity(hiddenCells.contains(row.id) ? 0.3 : 1)
				}
				
				Spacer()
			}
		}
		
		return content
	}
}


struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
		ContentView().previewLayout(.fixed(width: 200, height: 170))
    }
}