A SwiftUI code to demonstrate how to create a shadow view in SwiftUI

ShadowContainerView.swift

import SwiftUI

struct ShadowComponent: View {
    
    enum Direction {
        case upward
        case downward
        
        func getStartEndPoints() -> (start: UnitPoint, end: UnitPoint) {
            switch self {
            case .upward:
                return (.bottom, .top)
            case .downward:
                return (.top, .bottom)
            }
        }
    }
    
    let direction: Direction
    
    var body: some View {
        
        let startEndPoints = direction.getStartEndPoints()
        LinearGradient(colors: [
            Color.gray.opacity(0.5),
            Color.white.opacity(0.5)
        ], startPoint: startEndPoints.start, endPoint: startEndPoints.end).frame(height: 12)
    }
}

struct ShadowContainerView<Content: View>: View {
        
    let content: Content
    let shadowPosition: ShadowPosition
    
    enum ShadowPosition {
        case top
        case bottom
        case all
    }
    
    init(content: @escaping () -> Content,
         shadowPosition: ShadowPosition
    ) {
        self.content = content()
        self.shadowPosition = shadowPosition
    }
        
    var body: some View {
        VStack {
            if shadowPosition != .bottom  {
                ShadowComponent(direction: .upward)
            }
            content
            if shadowPosition != .top {
                ShadowComponent(direction: .downward)
            }
        }
    }
}

struct ShadowComponent_Previews: PreviewProvider {
    static var previews: some View {
        VStack(spacing: 16) {
            ShadowContainerView(content: {
                VStack {
                    Text("Section 1")
                    Text("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam").padding()
                }
            }, shadowPosition: .all)
            ShadowContainerView(content: {
                VStack {
                    Text("Section 2")
                    Text("Lorem ipsum dolor sit amet, coddectetur adidsding elit").padding()
                }
            }, shadowPosition: .all)
            ShadowContainerView(content: {
                VStack {
                    Text("Section 3")
                    Text("Lorem ipsumt. llamco laboris nisi ut aliquip ex ea commodo c").padding()
                }
            }, shadowPosition: .all)
            ShadowContainerView(content: {
                VStack {
                    Text("Section 4")
                    Text("Lorem ipsumt. llamco laboris nisi ut aliquip ex ea commodo c").padding()
                }
            }, shadowPosition: .all)
        }
    }
}