SwiftUI OnDestroy modifier

OnDestroy.swift

import SwiftUI

private struct OnDestroy: ViewModifier {
  let onDestroy: () -> Void
  final class Lifetime {
    var onDestroy: () -> Void = { }
    deinit { onDestroy() }
  }
  @State var lifetime: Lifetime = .init()
  func body(content: Content) -> some View {
    lifetime.onDestroy = onDestroy
    return content
      .background(Color.clear) //this needs to be actually different than content itself, else `body(content:)` wont even run (thanks to SwiftUI magic)
  }
}

extension View {
  func onDestroy(_ onDestroy: @escaping () -> Void) -> some View {
    self.modifier(OnDestroy(onDestroy: onDestroy))
  }
}