Undo/Redo with DragGesture

I have a sample macOS app that I'm working on. I can run the exactly same lines of code below for iOS. For now, I'm running code for macOS since I can just press Command + z to undo the last action.

Anyway, I have two Text View objects. Since TextView has the DragGesture gesture, I am able to freely move either of them. And I want to undo and redo their positions. So the following is what I have.

import SwiftUI

struct ContentView: View {
	@State var textViews: [TextView] = [TextView(text: "George"), TextView(text: "Susan")]

	var body: some View {
		VStack {
			ForEach(textViews, id: \.id) { textView in
				textView
			}
		}
	}
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

struct TextView: View {
	@Environment(\.undoManager) var undoManager
	@StateObject private var undoModel = UndoViewModel()

	@State private var dragOffset: CGSize = .zero
	@State private var position: CGSize = .zero

	let id = UUID()
	let text: String
	init(text: String) {
		self.text = text
	}
	var body: some View {
		ZStack {
			Text(text)
				.fixedSize()
				.padding(.vertical, 10)
				.offset(x: dragOffset.width + position.width, y: dragOffset.height + position.height)
				.gesture(
					DragGesture()
						.onChanged {
							self.dragOffset = $0.translation
						}
						.onEnded( { (value) in
							self.position.width += value.translation.width
							self.position.height += value.translation.height
							self.dragOffset = .zero
							undoModel.registerUndo(CGSize(width: position.width, height: position.height), in: undoManager)
						})
				)
		}
	}
}

class UndoViewModel: ObservableObject {
	@Published var point = CGSize.zero

	func registerUndo(_ newValue: CGSize, in undoManager: UndoManager?) {
		let oldValue = point
		undoManager?.registerUndo(withTarget: self) { [weak undoManager] target in
			target.point = oldValue // registers an undo operation to revert to old text
			target.registerUndo(oldValue, in: undoManager) // this makes redo possible
		}
		undoManager?.setActionName("Move")
		point = newValue // update the actual value
	}
}

Well, if I press Command + z after moving one of them, it won't return to the last position. What am I doing wrong? Muchos thankos.