chris.swift

import SwiftUI

extension View {
    func badge(num: Int) -> some View {
        return self.overlay(
            ZStack(alignment: .topTrailing) {
                    Circle()
                        .fill(Color.red)
                        .frame(width: 24, height: 24)
                        .overlay(Text(num.description))
                        .transition(.scale)
                    .alignmentGuide(.trailing) { dim -> CGFloat in
                        return dim[VerticalAlignment.center]
                    }
                    .alignmentGuide(VerticalAlignment.top) { dim -> CGFloat in
                        return dim[HorizontalAlignment.center]
                    }
            }
            , alignment: .topTrailing)
    }
}


struct ContentView : View {
    
    @State var badgeCount = 0
    
    var body: some View {
        VStack {
            Rectangle()
                .fill(Color.blue)
                .frame(width: 100, height: 100)
                .badge(num: badgeCount)
                .border(Color.green)
            Stepper("Update", value: $badgeCount.animation())
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}