RootView.swift

import SwiftUI

struct ViewProvider: Identifiable {
  var id: AnyHashable
  var type: Any
  var view: AnyView
  
  init<ViewType>(view: ViewType) where ViewType: View & Identifiable {
    self.id = view.id
    self.type = ViewType.self
    self.view = AnyView(erasing: view)
  }
  
  func content() -> AnyView {
    self.view
  }
}

struct ViewProviders: Sequence, Collection, BidirectionalCollection, RandomAccessCollection {
  struct Iterator: IteratorProtocol {
    var it: Int
    var endIndex: Int {
      elements.endIndex
    }
    
    let elements: [ViewProvider]
    
    init(elements: [ViewProvider]) {
      self.it = elements.startIndex
      self.elements = elements
    }
    
    mutating func next() -> ViewProvider? {
      guard it != endIndex else { return nil }
      defer { it += 1 }
      return elements[it]
    }
  }
  
  func makeIterator() -> Iterator {
    Iterator(elements: viewProviders)
  }
  
  private var viewProviders: [ViewProvider] = []
  
  var startIndex: Int {
    viewProviders.startIndex
  }

  var endIndex: Int {
    viewProviders.endIndex
  }

  func index(after i: Int) -> Int {
    viewProviders.index(after: i)
  }
  
  func index(before i: Int) -> Int {
    viewProviders.index(before: i)
  }

  subscript(position: Int) -> ViewProvider {
    get {
      viewProviders[position]
    }
    set {
      viewProviders[position] = newValue
    }
  }
}

struct RootView: View {
  var children: ViewProviders

  var body: some View {
    VStack {
      ForEach(children) {child in
        child.content()
      }
    }
  }
}