ViewController using Lua

LuaViewController.swift

import UIKit
import Lua

class LuaViewController: UIViewController {
    @IBOutlet weak var vPluginContainer: UIView!

    let vm = Lua.VirtualMachine()
    var startFunc: Function?
    var tickFunc: Function?
    var timer: Timer?
    
    private func loadLua() {
        vm.globals["addWidget"] = vm.createFunction([
            String.arg, // widget name
            Int64.arg, // tag
            Number.arg, // x coordinate
            Number.arg, // y coordinate
            Number.arg, // radius
            String.arg // color hex string
        ]) { (args) -> SwiftReturnValue in
            let (widgetName, widgetTag, xCoordinate, yCoordinate, radius, hexColor) = (
                args.string, args.integer, args.number, args.number, args.number, args.string
            )
            switch widgetName {
            case "Circle":
                let v = UIView(frame: CGRect(
                    x: xCoordinate.toDouble() - radius.toDouble(),
                    y: yCoordinate.toDouble() - radius.toDouble(),
                    width: radius.toDouble() * 2,
                    height: radius.toDouble() * 2))
                v.layer.cornerRadius = CGFloat(radius.toDouble())
                v.tag = Int(widgetTag)
                let uiColor = UIColor(hex: hexColor) ?? .black
                v.backgroundColor = uiColor
                self.vPluginContainer.addSubview(v)
                
            default:
                print("Unknown widget - \(widgetName)")
            }
            
            return .nothing
        }

        vm.globals["updateProperty"] = vm.createFunction([
            Int64.arg, // tag
            String.arg, // attribute name
            String.arg // attribute value
        ]) { (args) -> SwiftReturnValue in
            let (widgetTag, attributeName, attributeValue) = (
                args.integer, args.string, args.string
            )
            guard let w = self.vPluginContainer.viewWithTag(Int(widgetTag)) else { return .nothing }
            
            switch attributeName {
            case "color":
                if let color = UIColor(hex: attributeValue) {
                    w.backgroundColor = color
                }

            default:
                break
            }
            
            return .nothing
        }
        
        guard let luaSourcePath = Bundle.main.path(forResource: "luaPluginCode", ofType: "lua") else {
            print("LUA file not found")
            return
        }
        
        do {
            let luaCode = try String(contentsOfFile: luaSourcePath)
            let result = vm.createFunction(luaCode)
            switch result {
            case .value(let f):
                let fileRes = f.call([])
                switch fileRes {
                case .values(let values):
                    if values.count == 2 {
                        startFunc = values[0] as? Function
                        tickFunc = values[1] as? Function
                    } else {
                        print("Lua script must return 2 functions: start and tick")
                    }
                    
                case .error(let err):
                    print(err)
                }
                
            case .error(let err):
                print(err)
            }
        }
        catch {
            print(error.localizedDescription)
        }
    }

    @IBAction func runPlugin() {
        loadLua()

        _ = startFunc?.call([Double(vPluginContainer.bounds.width), Double(vPluginContainer.bounds.height)])

        timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(tick), userInfo: nil, repeats: true)
    }

    @objc func tick() {
        _ = tickFunc?.call([10.0])
    }
}