SwiftUI - How to preserve child view's state when updating parent view's state?

Question

I am trying to find a way to preserve the child view when the parent gets updated. I have the following setup:

struct VideoPlayerView: View {
       
    @State var fullScreen : Bool = false
    
    var body: some View {
        NavigationView {
            VStack {                
                PlayerContainerView(url: URL(string: "video-link-from-vimeo")!, fullScreen: $fullScreen)
                
                if !fullScreen {                    
                    VStack {
                        ...very long content here...
                    }                          
                }
            }
            .backgroundColor(self.fullScreen ? K.Colors.AppText : K.Colors.AppBackground)
            .hideNavigationBar()
        }
        .hideNavigationBar()
    }
}

PlayerContainerView is just my wrapper holding the AVPlayer and some custom controls. To display the player in the first place I am using this technique from Section 5. of this official SwiftUI Tutorial if that's relevant.

The video I am loading is from Vimeo. The fullScreen @State property is getting updated from the child view.

Wanted Result

I would like to be able to hide everything that's under my player so that the player is then displayed on full screen. This could happen at any time - ie when the video is already playing, when the video is paused at specific time etc.

The Issue

The issue is that if I update that the fullScreen @State property I get whole new View and actually if I was playing the video before entering full screen I am hearing it still play in the background. My full screen video is now starting from the beginning and not resuming from where it was before entering full screen.

Answer 1

The issue is that the state of AVPlayer is not restored between View updates. A possible solution is to provide the AVPlayer as a parameter to your PlayerContainerView (instead of the url).