Minimalistic example of Metal NSView with CAMetalLayer

MetalViewExample.swift

// A simple view with CAMetalLayer

protocol MetalViewDelegate: AnyObject {
    func viewDidResize()
}

class MetalView: NSView {
    weak var delegate: MetalViewDelegate?

    override var acceptsFirstResponder: Bool {
        true
    }

    override var frame: NSRect {
        didSet {
            delegate?.viewDidResize()
        }
    }

    override func viewDidChangeBackingProperties() {
        delegate?.viewDidResize()
    }

    override func makeBackingLayer() -> CALayer {
        return CAMetalLayer()
    }
}

// ViewController class setup to use metal rendering

class MetalViewController: NSViewController {
    init() {
        super.init(nibName: nil, bundle: nil)
        loadView()
    }
  
    required init?(coder _: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func loadView() {
        let view = MetalView()
        view.delegate = self
        view.wantsLayer = true
        view.layerContentsRedrawPolicy = .duringViewResize
        if let metalLayer = view.layer as? CAMetalLayer {
            metalLayer.pixelFormat = .bgra8Unorm
            metalLayer.framebufferOnly = true
            metalLayer.device = metalLayer.preferredDevice
            metalLayer.delegate = self
        }

        self.view = view
        viewDidLoad()
    }
  
    private var viewportSize: CGSize {
        return view.convertToBacking(view.bounds.size)
    }
  
    private func draw() {
        guard
            let metalLayer = view.layer as? CAMetalLayer,
            let drawable = metalLayer.nextDrawable() else {
            return
        }
        metalLayer.drawableSize = viewportSize
        let renderPass = MTLRenderPassDescriptor()
        renderPass.colorAttachments[0].clearColor = .init(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0)
        renderPass.colorAttachments[0].texture = drawable.texture
        renderPass.colorAttachments[0].loadAction = .clear
        renderPass.colorAttachments[0].storeAction = .store

        autoreleasepool {
            // render your scene here
        }
    }
    
    private func resize() {
        if let metalLayer = view.layer as? CAMetalLayer {
            metalLayer.drawableSize = viewportSize
        }
    }
}

extension MetalViewController: MetalViewDelegate {
    func viewDidResize() {
        resize()
    }
}

extension MetalViewController: CALayerDelegate {
    func display(_: CALayer) {
        draw()
    }
}