RenderView

gistfile1.txt

class RenderView: UIView {
    
    private var renderLayer: CALayer?
    
    func update(renderLayer: CALayer) {
        self.renderLayer = renderLayer
    }
    
    override func draw(_ rect: CGRect) {
        guard let renderLayer = renderLayer,
              let context = UIGraphicsGetCurrentContext() else { return }
        renderLayer.render(in: context)
    }
}

class ViewController: UIViewController {
    private lazy var renderView = RenderView()
    private var displayLink: CADisplayLink?
    
    // TODO: setup renderView in viewDidLoad();
    // TODO: add 'chartsPinnedView.update(renderLayer: renderLayer)' at place when 'renderLayer' is ready;
    // 'renderLayer' - layer that will recorded in renderView;
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        displayLink = CADisplayLink(target: self, selector: #selector(displayLink(_:)))
        displayLink?.add(to: RunLoop.main, forMode: RunLoop.Mode.common)
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        displayLink?.invalidate()
    }
    
    @objc private func displayLink(_ displayLink: CADisplayLink) {
        guard view.window != nil, !renderView.isHidden else { return }
        
        renderView.setNeedsDisplay()
    }
}