新建swift工程直接爆红，而且运行起来是黑屏的解决方法

1.在AppDelegate.swift里添加@available(iOS 13.0, *)，和var window: UIWindow?

@UIApplicationMain
  @available(iOS 13.0, *)
class AppDelegate: UIResponder, UIApplicationDelegate {


var window: UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

2.在SceneDelegate.swift添加@available(iOS 13.0, *)， var window: UIWindow?

import UIKit
@available(iOS 13.0, *)
class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
        guard let _ = (scene as? UIWindowScene) else { return }
    }