ContentView.swift

struct ContentView: View {

    @State private var initialOffset: CGFloat = 350.0
    @State private var initialOpacity: Double = 0.0
    private let duration = 5.0

    @ObservedObject var manager = MotionManager()


    var body: some View {
        GeometryReader(content: { geometry in
            ZStack {
                Image("background")
                    .resizable()
                    .scaledToFill()
                    .frame(width: geometry.size.width * 1.2, height: geometry.size.height * 1.2, alignment: .center)
                    .modifier(ParallaxModifier(magnitude: 20))
                    .ignoresSafeArea()
                LinearGradient(gradient: Gradient(colors: [.clear, .black]), startPoint: UnitPoint(x: 0.5, y: 0.35), endPoint: UnitPoint(x: 0.5, y: 1))
                VStack {
                    Spacer()
                    Text("Enjoy the world")
                        .font(.largeTitle)
                        .fontWeight(.semibold)
                        .foregroundColor(.white)
                        .padding(.bottom, 16)
                        .offset(x: initialOffset, y: 0)
                        .opacity(initialOpacity)

                    Text("We'll help you find the best experiences & adventures.")
                        .font(.headline)
                        .fontWeight(.light)
                        .foregroundColor(.white)
                        .multilineTextAlignment(.center)
                        .lineLimit(2)
                        .padding(.horizontal, 32.0)
                        .offset(x: initialOffset * 2.5, y: 0)
                        .opacity(initialOpacity)

                    Button("Continue", action: {})
                        .frame(width: 65, height: 65, alignment: .center)
                        .foregroundColor(.accentColor)
                        .background(Color.white)
                        .cornerRadius(8)
                        .opacity(initialOpacity)

                        .padding(.all, 16)
                }
                .modifier(ParallaxModifier(magnitude: 30))
                .padding()
                .frame(width: geometry.size.width, height: geometry.size.height, alignment: .bottom)
            }
            .frame(width: geometry.size.width, height: geometry.size.height, alignment: .center)
        })
        .onAppear {

            withAnimation(.easeInOut(duration: 1)) {
                self.initialOffset = 0
                self.initialOpacity = 1
            }
        }
    }
}