ContentView+Sliding.swift

struct ContentView: View {
    
    @State private var shouldShowErrorLabel = false
    
    init() {
        UINavigationBar.appearance().backgroundColor = .blue
        UINavigationBar.appearance().largeTitleTextAttributes = [
            .foregroundColor : UIColor.white,
        ]
    }
    
    var errorLabel: some View {
        HStack {
            Spacer()
            Text("Error!")
                .fontWeight(.bold)
                .foregroundColor(Color.white)
            Spacer()
        }
        .frame(height: 44.0)
        .background(Color.red)
    }
    
    var body: some View {
        NavigationView {
            VStack {
                if shouldShowErrorLabel {
                    errorLabel.transition(.asymmetric(insertion: .fadeAndSlide, removal: .fadeAndSlide))
                    Spacer()
                    Spacer()
                }
            }
            .navigationBarTitle("Home", displayMode: .large)
            .onAppear {
                self.animateAndDelayWithSeconds(1) { self.shouldShowErrorLabel = true }
                self.animateAndDelayWithSeconds(3) { self.shouldShowErrorLabel = false }
            }
        }
    }
    
    func animateAndDelayWithSeconds(_ seconds: TimeInterval, action: @escaping () -> Void) {
        DispatchQueue.main.asyncAfter(deadline: .now() + seconds) {
            withAnimation {
                action()
            }
        }
    }
}