When I run the simulator or check out the Canvas, this code shows nothing. I have SF Symbols installed on my Mac, and systemName: "mic" is an actual thing. I used SF Symbols in GuessTheFlag, Project 2 and it worked.

Why doesn't it show anything? The simulator screen is blank.

struct ContentView: View {

    var body: some View {
        Capsule()
            .strokeBorder(ImagePaint(image: Image(systemName: "mic"), scale: 0.9), lineWidth: 20)
            .frame(width: 300, height: 200)
    }
}

It is doing it. You need to have a different colour for the background to see the border.

Try this for example

Capsule()
    .strokeBorder(ImagePaint(image: Image(systemName: "mic"), scale: 0.9), lineWidth: 20)
    .background(Color.mint)
    .frame(width: 300, height: 200)

Then you could add this after the .frame

.clipShape(Capsule())