# Scene Coordinator and BindableType View Controllers Question

**URL:** <https://forums.kodeco.com/t/scene-coordinator-and-bindabletype-view-controllers-question/32902>\
**Category:** RxSwift\
**Created:** [August 3, 2017, 6:46pm UTC](https://forums.kodeco.com/t/scene-coordinator-and-bindabletype-view-controllers-question/32902 "2017-08-03T18:46:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mbopp](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/mbopp/32/70561_2.png) [@mbopp](https://forums.kodeco.com/u/mbopp)\
**Post date:** [August 3, 2017, 6:46pm UTC](https://forums.kodeco.com/t/scene-coordinator-and-bindabletype-view-controllers-question/32902/1 "2017-08-03T18:46:44Z")

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In chapter 24 a scene coordinator is used, which I really like the idea of in MVVM. My question is “Do all view controllers need to have a UINavigationController sitting in front of it?”

I ask this, because when I try to segue to another view controller (that does not have it’s own nav controller) I have issues with the mutating `bindViewModel` that should accept the View Model. I receive the error `Argument passed to call that takes no arguments` when calling `vc.bindViewModel(to: viewModel)`

```auto
    case .purchaseOrderList(let viewModel):
      let vc = storyboard.instantiateViewController(withIdentifier: "PurchaseOrderList") as! PurchaseOrderListViewController
// var vc = nc.viewControllers.first as! PurchaseOrderListViewController
      vc.bindViewModel(to: viewModel) // <--- ERROR: Argument passed to call that takes no arguments

```

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<div class="post-metadata">

**Author:** ![mbopp](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/mbopp/32/70561_2.png) [@mbopp](https://forums.kodeco.com/u/mbopp)\
**Post date:** [August 3, 2017, 7:44pm UTC](https://forums.kodeco.com/t/scene-coordinator-and-bindabletype-view-controllers-question/32902/2 "2017-08-03T19:44:46Z")

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I believe I’ve answered the question for the most part. The odd error was because I defined `vc` as immutable with `let`. Changing that to a mutable `var` resolved the issue. Just a bad error message.

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**Author:** ![system](https://s3.amazonaws.com/cdn.raywenderlich.com/community/forum-assets/noun-game-ghost-878668.png) [@system](https://forums.kodeco.com/u/system)\
**Post date:** [January 17, 2018, 10:46am UTC](https://forums.kodeco.com/t/scene-coordinator-and-bindabletype-view-controllers-question/32902/3 "2018-01-17T10:46:46Z")

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