NodeFor.swift

func view(_ view: ARSKView, nodeFor anchor: ARAnchor) -> SKNode? {
        
        if let imageAnchor = anchor as? ARImageAnchor,
            let referenceImageName = imageAnchor.referenceImage.name,
            let scannedImage =  self.images[referenceImageName] {
            
            self.selectedImage = scannedImage
            
            self.performSegue(withIdentifier: "showImageInformation", sender: self)
            
            return imageSeenMarker()
        }
        
        return nil
    }
    
    private func imageSeenMarker() -> SKLabelNode {
        let labelNode = SKLabelNode(text: "✅")
        labelNode.horizontalAlignmentMode = .center
        labelNode.verticalAlignmentMode = .center
        
        return labelNode
    }