A SwiftUI slideshow view

TVSlideshowView.swift

struct TVSlideshowView : View {
  let publisher : AnyPublisher<UIImage?, Never>
  
  @State private var uiImageA: UIImage? = nil
  @State private var uiImageB: UIImage? = nil
  @State private var imageAHasPriority: Bool = true
  
  var body: some View {
    ZStack {
      decorate(uiImage: uiImageA, isImageA: true)
      decorate(uiImage: uiImageB, isImageA: false)
    }
    .onAppear() {
      UIApplication.shared.isIdleTimerDisabled = true
    }
    .onDisappear() {
      UIApplication.shared.isIdleTimerDisabled = false
    }
    .onReceive(publisher) { uiImage in
      self.updateImages(uiImage:uiImage)
    }
  }
  
  func decorate(uiImage: UIImage?, isImageA: Bool) -> some View {
    Group {
      if uiImage != nil {
        decorate(uiImage: uiImage!, isImageA: isImageA)
      }
    }
  }
  
  func decorate(uiImage: UIImage, isImageA: Bool) -> some View {
    GeometryReader { proxy in
      Image(uiImage:uiImage)
        .renderingMode(.original)
        .resizable()
        .aspectRatio(contentMode: .fill)
        .frame(width:proxy.size.width, height:proxy.size.height)
        .animation(nil)
        .opacity(self.imageAHasPriority == isImageA ? 1.0 : 0.0)
        .animation(.easeOut(duration:0.6))
    }
  }
  
  func updateImages(uiImage: UIImage?) {
    if uiImage != nil {
      imageAHasPriority.toggle()
      if imageAHasPriority {
        uiImageA = uiImage
      } else {
        uiImageB = uiImage
      }
    }
  }
}