SwiftUI Vibrancy

ContentView.swift

import SwiftUI

@main
struct DemoVibrancyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}


struct ContentView: View {
    @State var level: Float = 0
    var body: some View {
        VStack(spacing: 12) {
            Group {
                Image(systemName: "plus.diamond.fill")
                    .resizable()
                    .frame(width: 140, height: 140)
                    .vibrancy(level)
                Text("Hello, world!")
                    .font(.system(size: 38, weight: .medium, design: .rounded))
                    .padding()
                    .vibrancy(level)
            }
            Slider(value: $level)
        }
        .padding(40)
        .background(VisualEffectView(material: .hudWindow))
    }
}

public struct Vibrancy: ViewModifier {
    
    let level: Double
    
    public func body(content: Content) -> some View {
        content
            .blendMode(.overlay)
            .overlay(content.opacity(1 - level))
    }
}

public extension View {
    
    func vibrancy(_ level: Float) -> some View {
        self.modifier(Vibrancy(level: Double(level)))
    }
    
}


public struct VisualEffectView: View {
    private var material: NSVisualEffectView.Material
    private var blendingMode: NSVisualEffectView.BlendingMode
    private var state: NSVisualEffectView.State
    
    public init(
        material: NSVisualEffectView.Material = .headerView,
        blendingMode: NSVisualEffectView.BlendingMode = .behindWindow,
        state: NSVisualEffectView.State = .followsWindowActiveState
    ) {
        self.material = material
        self.blendingMode = blendingMode
        self.state = state
    }
    
    public var body: some View {
        Representable(
            material: material,
            blendingMode: blendingMode,
            state: state
        ).accessibility(hidden: true)
    }
}

// MARK: - Representable
extension VisualEffectView {
    struct Representable: NSViewRepresentable {
        var material: NSVisualEffectView.Material
        var blendingMode: NSVisualEffectView.BlendingMode
        var state: NSVisualEffectView.State
        
        func makeNSView(context: Context) -> NSVisualEffectView {
            context.coordinator.visualEffectView
        }
        
        func updateNSView(_ view: NSVisualEffectView, context: Context) {
            context.coordinator.update(material: material)
            context.coordinator.update(blendingMode: blendingMode)
            context.coordinator.update(state: state)
        }
        
        func makeCoordinator() -> Coordinator {
            Coordinator()
        }
        
    }

    class Coordinator {
        let visualEffectView = NSVisualEffectView()
        
        init() {
            visualEffectView.blendingMode = .withinWindow
        }
        
        func update(material: NSVisualEffectView.Material) {
            visualEffectView.material = material
        }
        
        func update(blendingMode: NSVisualEffectView.BlendingMode) {
            visualEffectView.blendingMode = blendingMode
        }
        
        func update(state: NSVisualEffectView.State) {
            visualEffectView.state = state
        }
    }
}