A SwiftUI implementation of a simple radio group for iOS

RadioGroup+Example.swift

private struct ColorToggle: View {
    @Binding var isOn: Bool
    
    let color: Color
    
    var body: some View {
        Toggle("", isOn: $isOn)
            .toggleStyle(ColorToggleStyle(color: color))
            .buttonStyle(.borderless)
    }
}

private struct ColorToggleStyle: ToggleStyle {
    let color: Color
    
    func makeBody(configuration: Configuration) -> some View {
        Button(action: {
            configuration.isOn.toggle()
        }, label: {
            ZStack {
                Circle()
                    .fill(color)
                    .frame(width: 40, height: 40)
                
                if configuration.isOn {
                    Circle()
                        .stroke(color, lineWidth: 3)
                }
            }
            .frame(width: 48, height: 48)
        })
        .contentShape(Circle())
    }
}

struct ColorSwatchPickerView: View {
    let colors: [(Color, String)]
    
    private let columns = [
        GridItem(.adaptive(minimum: 48))
    ]
    
    @Binding var selectedColor: Color?
    
    var body: some View {
        LazyVGrid(columns: columns) {
            ForEach(colors, id: \.1) { color in
                ColorToggle(isOn: toggleBinding(color: color.0), color: color.0)
                    .accessibilityLabel(color.1)
            }
        }
    }
    
    private func toggleBinding(color: Color) -> Binding<Bool> {
        Binding(
            get: { selectedColor == color },
            set: { selected in selectedColor = selected ? color : nil }
        )
    }
}

struct ColorSwatchPickerView_Previews: PreviewProvider {
    struct ColorSwatchPickerExampleView: View {
        private let colors: [(Color, String)] = [
            (.red, "Red"),
            (.green, "Green"),
            (.orange, "Orange"),
            (.cyan, "Cyan"),
            (.indigo, "Indigo"),
            (.mint, "Mint"),
            (.pink, "Pink"),
            (.yellow, "Yellow"),
            (.teal, "Teal"),
            (.gray, "Gray")
        ]
        @State private var selectedColor: Color? = nil
        
        var body: some View {
            ColorSwatchPickerView(colors: colors, selectedColor: $selectedColor)
        }
    }
    
    static var previews: some View {
        Form {
            ColorSwatchPickerExampleView()
        }
    }
}

The trick is in converting the Binding<Color?> to a Binding<Bool> on line 54. Apart from that it's just a list of Toggle views.