How do you draw a border around a shape that is a series of paths in SwiftUI?

Question

I have a custom Shape in SwiftUI that is a series of CGPoints that form different lines.

I want to be able to draw a border around each individual path and right now the only thing I can think of is creating another Shape that takes the original CGPoints and adds x,y padding to each point but I wanted to see if there was another way that perhaps is built-in that I couldn't find.

For example, my shape is

      -----
           |
           |

and I want to add a border Shape so I can detect when someone is in a bound where the # represents a new possible Shape around the original paths.

     ######## 
     #----- #
      ######
          #|#
          #|#
           #

Is there a way to implement this that is built in?

edit: code I'm currently thinking about to draw the border, very early but gives a gist of what I'm thinking

struct DrawShapeBorder: Shape {
    var points: [CGPoint]

    func path(in rect: CGRect) -> Path {
        var path: Path = Path()

        guard let startingPoint = points.first else {
            return path
        }

        // go up
        let upStartingPoint = CGPoint(x: startingPoint.x, y: startingPoint.y + 5)
        path.move(to: upStartingPoint)

        for pointLocation in points {
            
            path.addLine(to: pointLocation)
        }

        return path
    }
}

Answer 1

As @Evergreen suggested in the comments, you can use the stroke modifier... but the tricky thing is that you can only apply one of these, so you can't do .stroke().stroke().stroke(), unlike .shadow().shadow().shadow().

However, you can work around this by using a ZStack containing 2 copies of the shape, then adding a different stroke to each of them.

struct ContentView: View {
    var body: some View {
        DrawShapeBorder(points: [
            CGPoint(x: 100, y: 150),
            CGPoint(x: 300, y: 100),
            CGPoint(x: 300, y: 200),
            CGPoint(x: 100, y: 200)
        ])
        .stroked()
    }
}
struct DrawShapeBorder: Shape {
    
    /// add the double border
    func stroked() -> some View {
        ZStack {
            self.stroke(Color.red, style: StrokeStyle(lineWidth: 20, lineCap: .round, lineJoin: .round))
            self.stroke(Color.white, style: StrokeStyle(lineWidth: 10, lineCap: .round, lineJoin: .round))
        }
    }
    
    var points: [CGPoint]
    
    func path(in rect: CGRect) -> Path {
        var path: Path = Path()
        
        guard let startingPoint = points.first else {
            return path
        }
        
        // go up
        let upStartingPoint = CGPoint(x: startingPoint.x, y: startingPoint.y + 5)
        path.move(to: upStartingPoint)
        
        for pointLocation in points {
            path.addLine(to: pointLocation)
        }
        
        return path
    }
}

Result: