OnLayout Tutorial 06

OnLayout Tutorial 06.swift

struct MainView: View {
    
    /// Controls the amount of padding above the scroll view's
    /// content.
    @State var titleBarHeight: CGFloat = 123
    
    var body: some View {
       ScrollView {
            HStack {
                Spacer()
                Text("ScrollView Content")
                    .multilineTextAlignment(.center)
                    .foregroundColor(.white)
                    .background(Color.blue.brightness(0.2))
                Spacer()
            }
            /// Pad the top of the content based on the value
            /// of `titleBarHeight`.
            .padding(.top, titleBarHeight)
        }
        .background(Color.blue)
        .overlay(
            TitleBar()
                .background(
                    /// `proxy` will contain the size of the
                    /// title bar view.
                    GeometryReader { proxy in
                        Color.clear
                            .onAppear {
                                /// This updates the height when
                                /// the view first appears.
                                titleBarHeight = proxy.size.height
                            }
                    }
                ),
            alignment: .top
        )
        .edgesIgnoringSafeArea(.all)
    }
}