A source code to demonstrate how to apply rounded corner, rounded borders and shadow to a SwiftUI view

RoundedCornerBorderAndShadowStyles.swift

// An utility view extension
extension View {
    @ViewBuilder
    func `if`<Transform: View>(_ condition: Bool, transform: (Self) -> Transform) -> some View {
        if condition { transform(self) }
        else { self }
    }
}

// View modifier implementation
struct RoundedCornerWithShadowModifier: ViewModifier {

    let contentPadding: CGFloat
    let cornerRadius: CGFloat
    let isShadow: Bool
    let borderColor: Color
    let borderWidth: CGFloat

    init(contentPadding: CGFloat = 12.0, cornerRadius: CGFloat, isShadow: Bool = false, borderColor: Color, borderWidth: CGFloat) {
        self.contentPadding = contentPadding
        self.cornerRadius = cornerRadius
        self.isShadow = isShadow
        self.borderColor = borderColor
        self.borderWidth = borderWidth
    }

    func body(content: Content) -> some View {
        content
            .padding(contentPadding)
            .background(
                RoundedRectangle(cornerRadius: cornerRadius)
                    .fill(Color.green)
                    .if(isShadow) { $0.shadow(color: Color.black.opacity(0.5), radius: 12, x: 0, y: 0)
                    }
            )
            .overlay(
                RoundedRectangle(cornerRadius: cornerRadius)
                    .stroke(Color.red, lineWidth: borderWidth)
            )
    }
}

// Rounded corner with shadow demo code
struct RoundedCornerWithShadow: View {
    var body: some View {
        Text("Hello World")
            .modifier(RoundedCornerWithShadowModifier(cornerRadius: 12.0, isShadow: true, borderColor: .red, borderWidth: 1.0))
    }
}